🚨 CVE-2026-74622
In the Linux kernel, the following vulnerability has been resolved:
net: atlantic: free RX pages of consumed but not refilled buffers
aq_ring_rx_deinit() only walks [sw_head, sw_tail), the region posted to
hardware. Since the page reuse strategy was added, a cleaned RX buffer
keeps its page (and its DMA mapping) in the ring for reuse, and refill
is batched: aq_ring_rx_fill() returns early until AQ_CFG_RX_REFILL_THRES
slots are free. Slots that were consumed but not yet reposted therefore
sit in the complementary [sw_tail, sw_head) gap with a live page, and
the deinit walk never visits them: up to a refill batch worth of pages
and DMA mappings leak on every interface down.
Walk the whole ring instead and release whatever is still there. Also
bail out if the buffer ring is already gone: a partial
aq_ptp_ring_alloc() failure frees the ring but leaves aq_nic set, so
aq_ptp_ring_deinit() still gets here on the unwind path.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net: atlantic: free RX pages of consumed but not refilled buffers
aq_ring_rx_deinit() only walks [sw_head, sw_tail), the region posted to
hardware. Since the page reuse strategy was added, a cleaned RX buffer
keeps its page (and its DMA mapping) in the ring for reuse, and refill
is batched: aq_ring_rx_fill() returns early until AQ_CFG_RX_REFILL_THRES
slots are free. Slots that were consumed but not yet reposted therefore
sit in the complementary [sw_tail, sw_head) gap with a live page, and
the deinit walk never visits them: up to a refill batch worth of pages
and DMA mappings leak on every interface down.
Walk the whole ring instead and release whatever is still there. Also
bail out if the buffer ring is already gone: a partial
aq_ptp_ring_alloc() failure frees the ring but leaves aq_nic set, so
aq_ptp_ring_deinit() still gets here on the unwind path.
🎖@cveNotify
🚨 CVE-2026-74623
In the Linux kernel, the following vulnerability has been resolved:
net: atlantic: free stranded TX buffers on ring deinit
aq_vec_deinit() drains the TX rings with a single aq_ring_tx_clean()
call, which frees at most AQ_CFG_TX_CLEAN_BUDGET (256) descriptors and
stops at hw_head, which no longer moves once aq_vec_stop() has stopped
the hardware and NAPI. Completed descriptors beyond the budget and
everything still posted in [hw_head, sw_tail) keep their skb or
xdp_frame when the interface goes down: aq_vec_ring_free() then frees
the buffer ring and the references are lost for good.
Today this is a silent memory leak on every interface down under
TX/XDP_TX load. With the conversion of the RX path to page_pool posted
for net-next it becomes much more visible: XDP_TX frames carry fragment
references on the RX ring's page_pool, so a single stranded frame keeps
the pool's inflight count above zero forever. page_pool_destroy() then
never completes, the pool is leaked together with its pages, and
"page_pool_release_retry() stalled pool shutdown" is warned every 60
seconds from that point on, on every ifdown, XDP detach or ring resize
under XDP_TX load.
Bring back aq_ring_tx_deinit() as it was before the removal and use it
for teardown again, with one extension: TX rings can hold xdp_frames
nowadays, so release those too. They are returned with
xdp_return_frame() since this runs in process context.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net: atlantic: free stranded TX buffers on ring deinit
aq_vec_deinit() drains the TX rings with a single aq_ring_tx_clean()
call, which frees at most AQ_CFG_TX_CLEAN_BUDGET (256) descriptors and
stops at hw_head, which no longer moves once aq_vec_stop() has stopped
the hardware and NAPI. Completed descriptors beyond the budget and
everything still posted in [hw_head, sw_tail) keep their skb or
xdp_frame when the interface goes down: aq_vec_ring_free() then frees
the buffer ring and the references are lost for good.
Today this is a silent memory leak on every interface down under
TX/XDP_TX load. With the conversion of the RX path to page_pool posted
for net-next it becomes much more visible: XDP_TX frames carry fragment
references on the RX ring's page_pool, so a single stranded frame keeps
the pool's inflight count above zero forever. page_pool_destroy() then
never completes, the pool is leaked together with its pages, and
"page_pool_release_retry() stalled pool shutdown" is warned every 60
seconds from that point on, on every ifdown, XDP detach or ring resize
under XDP_TX load.
Bring back aq_ring_tx_deinit() as it was before the removal and use it
for teardown again, with one extension: TX rings can hold xdp_frames
nowadays, so release those too. They are returned with
xdp_return_frame() since this runs in process context.
🎖@cveNotify
🚨 CVE-2026-74624
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack: defer invalid log until after unlock
TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock
is still held.
When invalid logging is routed to nfnetlink_log and conntrack export is
enabled, the log path can re-enter conntrack netlink glue and dump the
same conntrack again. Protocol attribute dumping may take ct->lock, so
logging while holding that lock can deadlock.
Defer the TCP invalid logs by storing only the minimal log context while
ct->lock is held and emitting the log after unlocking. Also make the TCP
timeout-lowering invalid path return whether a log is needed, then emit
that log after unlocking.
Do the same for the SCTP invalid state-transition log that can be reached
while ct->lock is held.
Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers
that log invalid conntracks while holding ct->lock are caught outside TCP
and SCTP as well.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack: defer invalid log until after unlock
TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock
is still held.
When invalid logging is routed to nfnetlink_log and conntrack export is
enabled, the log path can re-enter conntrack netlink glue and dump the
same conntrack again. Protocol attribute dumping may take ct->lock, so
logging while holding that lock can deadlock.
Defer the TCP invalid logs by storing only the minimal log context while
ct->lock is held and emitting the log after unlocking. Also make the TCP
timeout-lowering invalid path return whether a log is needed, then emit
that log after unlocking.
Do the same for the SCTP invalid state-transition log that can be reached
while ct->lock is held.
Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers
that log invalid conntracks while holding ct->lock are caught outside TCP
and SCTP as well.
🎖@cveNotify
🚨 CVE-2026-74626
In the Linux kernel, the following vulnerability has been resolved:
NTB: ntb_netdev: Preserve RX queue depth on allocation failure
ntb_netdev_rx_handler() hands the received skb to the network stack
before allocating its replacement. If the allocation fails, nothing is
reposted. Every failure therefore takes one buffer out of the RX queue
while the interface remains up, and enough failures eventually stall
reception.
A retry path could refill the queue later, but ntb_netdev has none.
Allocate the replacement first instead. If that fails, drop the packet
and repost the same skb. This keeps the queue full and lets packet
delivery resume as soon as memory is available again.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
NTB: ntb_netdev: Preserve RX queue depth on allocation failure
ntb_netdev_rx_handler() hands the received skb to the network stack
before allocating its replacement. If the allocation fails, nothing is
reposted. Every failure therefore takes one buffer out of the RX queue
while the interface remains up, and enough failures eventually stall
reception.
A retry path could refill the queue later, but ntb_netdev has none.
Allocate the replacement first instead. If that fails, drop the packet
and repost the same skb. This keeps the queue full and lets packet
delivery resume as soon as memory is available again.
🎖@cveNotify
🚨 CVE-2026-74627
In the Linux kernel, the following vulnerability has been resolved:
net: devmem: prevent net-iov / page mixing
We should either have net_iov or page backed frags in a single skb,
otherwise it blows up down the stack. Don't allow mixing in
zerocopy_fill_skb_from_devmem().
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net: devmem: prevent net-iov / page mixing
We should either have net_iov or page backed frags in a single skb,
otherwise it blows up down the stack. Don't allow mixing in
zerocopy_fill_skb_from_devmem().
🎖@cveNotify
🚨 CVE-2026-74628
In the Linux kernel, the following vulnerability has been resolved:
net/x25: fix use-after-free of the socket by its timers
The x25 timers are armed with mod_timer() and cancelled with
timer_delete(), so a pending timer holds no reference on the socket and a
cancel does not wait for a callback already running on another CPU.
x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall
sk->sk_timer after __x25_destroy_socket() has passed its cancel point.
The following __sock_put() frees the socket while the timer is still
queued, and the next expiry uses freed memory. KASAN reports a
slab-use-after-free on the kmalloc-2k object freed by close().
timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and
x25_timer_expiry() both reach the cancels from inside the timer they
would wait on, through __x25_destroy_socket() and x25_disconnect().
Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer()
so that an armed timer owns a reference, and release it in both expiry
handlers. Rearm the heartbeat only while sk_hashed(sk) is still true,
since __x25_destroy_socket() unlinks the socket before dropping it. Arm
the deferred destroy timer the same way and drop its reference in
x25_destroy_timer().
Reproduced on net with KASAN, with the heartbeat period shortened so the
window recurs. With this patch the reproducer no longer triggers a
report and /proc/net/x25 drains.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net/x25: fix use-after-free of the socket by its timers
The x25 timers are armed with mod_timer() and cancelled with
timer_delete(), so a pending timer holds no reference on the socket and a
cancel does not wait for a callback already running on another CPU.
x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall
sk->sk_timer after __x25_destroy_socket() has passed its cancel point.
The following __sock_put() frees the socket while the timer is still
queued, and the next expiry uses freed memory. KASAN reports a
slab-use-after-free on the kmalloc-2k object freed by close().
timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and
x25_timer_expiry() both reach the cancels from inside the timer they
would wait on, through __x25_destroy_socket() and x25_disconnect().
Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer()
so that an armed timer owns a reference, and release it in both expiry
handlers. Rearm the heartbeat only while sk_hashed(sk) is still true,
since __x25_destroy_socket() unlinks the socket before dropping it. Arm
the deferred destroy timer the same way and drop its reference in
x25_destroy_timer().
Reproduced on net with KASAN, with the heartbeat period shortened so the
window recurs. With this patch the reproducer no longer triggers a
report and /proc/net/x25 drains.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74629
In the Linux kernel, the following vulnerability has been resolved:
net/dibs: Correct freeing of dmb_clientid_arr
A dibs device interrupt handler can be active after dibs_dev_del() and
may still access dmb_clientid_arr. (UAF)
In case of a failure in dibs_dev_add() being called by dibs_lo_dev_probe()
dmb_clientid_arr is freed twice (double free).
Free dmb_clientid_arr in dibs_dev_release() after last reference is gone.
Note that allocating in dibs_dev_add() instead of dibs_dev_alloc() is ok
for now, because no dmbs can be registered before dibs_dev_add().
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net/dibs: Correct freeing of dmb_clientid_arr
A dibs device interrupt handler can be active after dibs_dev_del() and
may still access dmb_clientid_arr. (UAF)
In case of a failure in dibs_dev_add() being called by dibs_lo_dev_probe()
dmb_clientid_arr is freed twice (double free).
Free dmb_clientid_arr in dibs_dev_release() after last reference is gone.
Note that allocating in dibs_dev_add() instead of dibs_dev_alloc() is ok
for now, because no dmbs can be registered before dibs_dev_add().
🎖@cveNotify
🚨 CVE-2026-74630
In the Linux kernel, the following vulnerability has been resolved:
ipv6: prevent in6_dev_get() from resurrecting inet6_dev
in6_dev_get() reads dev->ip6_ptr under RCU and then unconditionally
increments its refcount. Device teardown can clear the pointer and drop
the last reference between these operations. The increment then
resurrects an object whose RCU free has already been queued, so callers
can use it after it is freed.
Use refcount_inc_not_zero() and return NULL when the object has already
reached zero. RCU keeps the memory accessible through the attempted
reference acquisition, and a successful increment pins the object for
the caller.
An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3)
kernel reproduced the invalid reference acquisition as UID 1000:
refcount_t: addition on 0; use-after-free.
ip6_mc_source+0xef4/0x17e0
It was followed by the corresponding reference underflow in
ip6_mc_source(). The supplied trace from the same unpatched revision
additionally shows the access after the RCU read-side section ends:
BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0
Write of size 8 at addr ffff888015b50240 by task poc/1219
Bug found and triaged by OpenAI Security Research and
validated by Trail of Bits.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ipv6: prevent in6_dev_get() from resurrecting inet6_dev
in6_dev_get() reads dev->ip6_ptr under RCU and then unconditionally
increments its refcount. Device teardown can clear the pointer and drop
the last reference between these operations. The increment then
resurrects an object whose RCU free has already been queued, so callers
can use it after it is freed.
Use refcount_inc_not_zero() and return NULL when the object has already
reached zero. RCU keeps the memory accessible through the attempted
reference acquisition, and a successful increment pins the object for
the caller.
An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3)
kernel reproduced the invalid reference acquisition as UID 1000:
refcount_t: addition on 0; use-after-free.
ip6_mc_source+0xef4/0x17e0
It was followed by the corresponding reference underflow in
ip6_mc_source(). The supplied trace from the same unpatched revision
additionally shows the access after the RCU read-side section ends:
BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0
Write of size 8 at addr ffff888015b50240 by task poc/1219
Bug found and triaged by OpenAI Security Research and
validated by Trail of Bits.
🎖@cveNotify
🚨 CVE-2026-74631
In the Linux kernel, the following vulnerability has been resolved:
net: smc: fix splice entry lifetime imbalance in smc_rx_splice
smc_rx_splice() passes pages to splice_to_pipe() before taking the
references that cover the lifetime of each splice entry. In the
VM-backed RMB path, splice_to_pipe() may drop unqueued entries through
smc_rx_spd_release(), while queued entries are released later via the
pipe buffer callback.
The old post-splice accounting also derives the number of queued VM pages
from an offset mutated while building the descriptor, and a multi-page
splice pairs one sock_hold() with multiple sock_put() calls.
Take the page and socket references for every candidate entry before
splice_to_pipe(), and drop the matching private state, page reference,
and socket reference from smc_rx_spd_release() for entries that never
get queued. This fixes a refcount imbalance that can underflow page
refcounts and trigger a use-after-free.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net: smc: fix splice entry lifetime imbalance in smc_rx_splice
smc_rx_splice() passes pages to splice_to_pipe() before taking the
references that cover the lifetime of each splice entry. In the
VM-backed RMB path, splice_to_pipe() may drop unqueued entries through
smc_rx_spd_release(), while queued entries are released later via the
pipe buffer callback.
The old post-splice accounting also derives the number of queued VM pages
from an offset mutated while building the descriptor, and a multi-page
splice pairs one sock_hold() with multiple sock_put() calls.
Take the page and socket references for every candidate entry before
splice_to_pipe(), and drop the matching private state, page reference,
and socket reference from smc_rx_spd_release() for entries that never
get queued. This fixes a refcount imbalance that can underflow page
refcounts and trigger a use-after-free.
🎖@cveNotify
🚨 CVE-2026-74632
In the Linux kernel, the following vulnerability has been resolved:
mm/huge_memory: fix huge_zero_pfn race
Patch series "mm/huge_memory: fix huge_zero_pfn race", v2.
There is a subtle race in the reference-counted huge_zero_folio
implementation.
The fast path atomic logic fails to account for the fact that the shrinker
(which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn
with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a
racing get_huge_zero_folio() installed a valid value there.
This results in huge_zero_folio being correctly set but huge_zero_pfn
being set incorrectly and thus is_huge_zero_pfn() and consequently
is_huge_zero_pmd() will misidentify the huge zero folio as being an
ordinary THP folio.
This can result in the huge zero folio being split and otherwise treated
incorrectly.
The solution to this is very subtle as there is an atomic fast path, and
thus ordering in weakly ordered architectures has to be treated very
carefully.
The first commit fixes the issue by introducing a spinlock around
huge_zero_[pfn, folio, refcount] write, with careful consideration paid to
load/store ordering in the fast path. It is placed first and kept as
small as possible so that it can be backported on its own.
The second commit is a pure cleanup which reworks the
CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent
logic from the dynamically allocated one.
This patch (of 2):
If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted
by huge_zero_refcount and returned by mm_get_huge_zero_folio().
When the caller is done with the huge zero page, its reference count is
decremented. Only a shrinker can set the reference count to zero.
A race can unfortunately occur between a shrinker decrementing the
reference count to zero and a concurrent page fault.
This is because shrink_huge_zero_folio_scan() might, if very unlucky, be
preempted between setting huge_zero_refcount to zero and writing an
invalid value.
During this time get_huge_zero_folio() could write to huge_zero_pfn before
shrink_huge_zero_folio_scan() resumes.
In this event the huge zero folio will be persistently misidentified
causing the THP code path to be entered inappropriately for the huge zero
folio:
CPU 0 CPU 1
=======================================|=================================
shrink_huge_zero_folio_scan() |
atomic_cmpxchg() sets refcount to 0 |
xchg() sets huge_zero_folio to NULL | get_huge_zero_folio()
| | atomic_inc_not_zero() -> zero
preempted for a long time | Allocate new huge zero folio
| | Write valid huge_zero_folio
v | Write valid huge_zero_pfn
Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite!
This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly
returning false for a huge zero page which could result in issues like the
huge zero folio being incorrectly split.
Note that the issue is with huge_zero_pfn not huge_zero_folio, as
get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL
with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set
huge_zero_folio.
Fix the issue by introducing a spinlock, huge_zero_lock, to prevent
concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount.
There needs to be significant care taken here to ensure correctness:
The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which
is outside of the critical section, and means huge zero allocation is
gated on zero huge_zero_refcount.
The fast path doesn't use huge_zero_lock, so the critical section is
irrelevant to it.
So invariants are required - huge_zero_refcount MUST:
* Only be set in the huge_zero_lock critical section to ensure
serialisation of huge_zero_pfn, huge_zero_folio and
---truncated---
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
mm/huge_memory: fix huge_zero_pfn race
Patch series "mm/huge_memory: fix huge_zero_pfn race", v2.
There is a subtle race in the reference-counted huge_zero_folio
implementation.
The fast path atomic logic fails to account for the fact that the shrinker
(which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn
with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a
racing get_huge_zero_folio() installed a valid value there.
This results in huge_zero_folio being correctly set but huge_zero_pfn
being set incorrectly and thus is_huge_zero_pfn() and consequently
is_huge_zero_pmd() will misidentify the huge zero folio as being an
ordinary THP folio.
This can result in the huge zero folio being split and otherwise treated
incorrectly.
The solution to this is very subtle as there is an atomic fast path, and
thus ordering in weakly ordered architectures has to be treated very
carefully.
The first commit fixes the issue by introducing a spinlock around
huge_zero_[pfn, folio, refcount] write, with careful consideration paid to
load/store ordering in the fast path. It is placed first and kept as
small as possible so that it can be backported on its own.
The second commit is a pure cleanup which reworks the
CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent
logic from the dynamically allocated one.
This patch (of 2):
If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted
by huge_zero_refcount and returned by mm_get_huge_zero_folio().
When the caller is done with the huge zero page, its reference count is
decremented. Only a shrinker can set the reference count to zero.
A race can unfortunately occur between a shrinker decrementing the
reference count to zero and a concurrent page fault.
This is because shrink_huge_zero_folio_scan() might, if very unlucky, be
preempted between setting huge_zero_refcount to zero and writing an
invalid value.
During this time get_huge_zero_folio() could write to huge_zero_pfn before
shrink_huge_zero_folio_scan() resumes.
In this event the huge zero folio will be persistently misidentified
causing the THP code path to be entered inappropriately for the huge zero
folio:
CPU 0 CPU 1
=======================================|=================================
shrink_huge_zero_folio_scan() |
atomic_cmpxchg() sets refcount to 0 |
xchg() sets huge_zero_folio to NULL | get_huge_zero_folio()
| | atomic_inc_not_zero() -> zero
preempted for a long time | Allocate new huge zero folio
| | Write valid huge_zero_folio
v | Write valid huge_zero_pfn
Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite!
This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly
returning false for a huge zero page which could result in issues like the
huge zero folio being incorrectly split.
Note that the issue is with huge_zero_pfn not huge_zero_folio, as
get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL
with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set
huge_zero_folio.
Fix the issue by introducing a spinlock, huge_zero_lock, to prevent
concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount.
There needs to be significant care taken here to ensure correctness:
The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which
is outside of the critical section, and means huge zero allocation is
gated on zero huge_zero_refcount.
The fast path doesn't use huge_zero_lock, so the critical section is
irrelevant to it.
So invariants are required - huge_zero_refcount MUST:
* Only be set in the huge_zero_lock critical section to ensure
serialisation of huge_zero_pfn, huge_zero_folio and
---truncated---
🎖@cveNotify
🚨 CVE-2026-74633
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix NULL pointer dereference in module event cache removal
A module-only event filter such as ":mod:foo" is cached with a NULL
event_mod->match when foo has not been loaded. If a later write tries to
remove a specific match from the same module, remove_cache_mod() passes
the NULL cached match to strcmp(), causing a NULL pointer dereference.
The issue can be reproduced from userspace:
echo ':mod:trace_events_kunit_missing' > /sys/kernel/tracing/set_event
echo '!foo_bar:mod:trace_events_kunit_missing' >> /sys/kernel/tracing/set_event
The second write must be a concatenation (">>") to not include O_TRUNC as
that would cause ftrace_clear_events() to clear the cached modules lines.
The crash was reproduced on x86_64 QEMU while KUnit workers contended on
the event tracing path:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
RIP: 0010:strcmp+0x10/0x30
Call Trace:
__ftrace_set_clr_event_nolock+0x373/0x4a0
ftrace_set_clr_event+0xf0/0x180
ftrace_event_write+0xdf/0x110
vfs_write+0xf6/0x440
ksys_write+0x68/0xe0
do_syscall_64+0xf9/0x540
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Check event_mod->match before comparing it, consistent with the existing
NULL checks for the cached system and event fields. The mismatched removal
continues to return -EINVAL; a broad cached module filter is removed with
"!:mod:<module>".
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix NULL pointer dereference in module event cache removal
A module-only event filter such as ":mod:foo" is cached with a NULL
event_mod->match when foo has not been loaded. If a later write tries to
remove a specific match from the same module, remove_cache_mod() passes
the NULL cached match to strcmp(), causing a NULL pointer dereference.
The issue can be reproduced from userspace:
echo ':mod:trace_events_kunit_missing' > /sys/kernel/tracing/set_event
echo '!foo_bar:mod:trace_events_kunit_missing' >> /sys/kernel/tracing/set_event
The second write must be a concatenation (">>") to not include O_TRUNC as
that would cause ftrace_clear_events() to clear the cached modules lines.
The crash was reproduced on x86_64 QEMU while KUnit workers contended on
the event tracing path:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
RIP: 0010:strcmp+0x10/0x30
Call Trace:
__ftrace_set_clr_event_nolock+0x373/0x4a0
ftrace_set_clr_event+0xf0/0x180
ftrace_event_write+0xdf/0x110
vfs_write+0xf6/0x440
ksys_write+0x68/0xe0
do_syscall_64+0xf9/0x540
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Check event_mod->match before comparing it, consistent with the existing
NULL checks for the cached system and event fields. The mismatched removal
continues to return -EINVAL; a broad cached module filter is removed with
"!:mod:<module>".
🎖@cveNotify
🚨 CVE-2026-74634
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Prevent subbuf order change when resizing is disabled
Because ring_buffer_subbuf_order_set() frees buffer pages, we can't
allow it when resizing is disabled. A non-consuming reader is at risk of
use-after-free (rb_advance_iter()).
Return -EBUSY on resize_disabled, matching ring_buffer_resize()
behaviour.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Prevent subbuf order change when resizing is disabled
Because ring_buffer_subbuf_order_set() frees buffer pages, we can't
allow it when resizing is disabled. A non-consuming reader is at risk of
use-after-free (rb_advance_iter()).
Return -EBUSY on resize_disabled, matching ring_buffer_resize()
behaviour.
🎖@cveNotify
🚨 CVE-2026-74635
In the Linux kernel, the following vulnerability has been resolved:
fbdev: bitblit: bound-check glyph index in bit_cursor()
bit_cursor() fetches the glyph under the cursor with
c = scr_readw(vc_pos);
src = vc_font.data + ((c & charmask) * w * height);
where charmask is 0x1ff when vc_hi_font_mask is set. The screen buffer
value comes directly from scr_readw() and may be larger than the current
font's glyph count.
Syzkaller triggers this via vcs_write(). The Call Trace shows
vcs_write() in vc_screen.c writing an arbitrary 16-bit value with
writev() to /dev/vcsa, which vcs_write_buf() in vc_screen.c stores via
vcs_scr_writew() without checking charcount. The stored value is later
read in bit_cursor() in bitblit.c.
When the font is changed from a font with 512 glyphs to a font with
256 glyphs, the screen buffer can retain characters with the high
bit set from the previous mode, which could also produce the same
out-of-bounds access.
BUG: KASAN: global-out-of-bounds in soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
Read of size 16 at addr ffff800086c57970
Call Trace:
soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
bit_cursor+0xa90/0x1108 drivers/video/fbdev/core/bitblit.c:365
fbcon_cursor+0x344/0x498 drivers/video/fbdev/core/fbcon.c:1427
hide_cursor+0xdc/0x2d0 drivers/tty/vt/vt.c:883
update_region+0x100/0x18c drivers/tty/vt/vt.c:669
vcs_write+0x8ec/0xaf0 drivers/tty/vt/vc_screen.c:685
bit_putcs_aligned() and bit_putcs_unaligned() already clamp the glyph
index to vc_font.charcount. Apply the same clamp in bit_cursor() after
extracting the attribute and masking, before indexing fontdata.
The fix completes the bounds checking started in commit 18c4ef4e765a
("fbdev: bitblit: bound-check glyph index in bit_putcs*"), which missed
the cursor path.
This change should be safe because the clamp reuses the existing
contract from fbcon: charcount is maintained under console_lock in
con_font_set() and fbcon_font_set(), and hi_font_mask is cleared when
switching from 512 to 256 glyphs. When stale screen data with high bits
remains after a font switch, or when vcs_write() stores an arbitrary
value, clamping the index to 0 prevents the out-of-bounds read without
changing cursor semantics — the same fallback bit_putcs uses.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
fbdev: bitblit: bound-check glyph index in bit_cursor()
bit_cursor() fetches the glyph under the cursor with
c = scr_readw(vc_pos);
src = vc_font.data + ((c & charmask) * w * height);
where charmask is 0x1ff when vc_hi_font_mask is set. The screen buffer
value comes directly from scr_readw() and may be larger than the current
font's glyph count.
Syzkaller triggers this via vcs_write(). The Call Trace shows
vcs_write() in vc_screen.c writing an arbitrary 16-bit value with
writev() to /dev/vcsa, which vcs_write_buf() in vc_screen.c stores via
vcs_scr_writew() without checking charcount. The stored value is later
read in bit_cursor() in bitblit.c.
When the font is changed from a font with 512 glyphs to a font with
256 glyphs, the screen buffer can retain characters with the high
bit set from the previous mode, which could also produce the same
out-of-bounds access.
BUG: KASAN: global-out-of-bounds in soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
Read of size 16 at addr ffff800086c57970
Call Trace:
soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
bit_cursor+0xa90/0x1108 drivers/video/fbdev/core/bitblit.c:365
fbcon_cursor+0x344/0x498 drivers/video/fbdev/core/fbcon.c:1427
hide_cursor+0xdc/0x2d0 drivers/tty/vt/vt.c:883
update_region+0x100/0x18c drivers/tty/vt/vt.c:669
vcs_write+0x8ec/0xaf0 drivers/tty/vt/vc_screen.c:685
bit_putcs_aligned() and bit_putcs_unaligned() already clamp the glyph
index to vc_font.charcount. Apply the same clamp in bit_cursor() after
extracting the attribute and masking, before indexing fontdata.
The fix completes the bounds checking started in commit 18c4ef4e765a
("fbdev: bitblit: bound-check glyph index in bit_putcs*"), which missed
the cursor path.
This change should be safe because the clamp reuses the existing
contract from fbcon: charcount is maintained under console_lock in
con_font_set() and fbcon_font_set(), and hi_font_mask is cleared when
switching from 512 to 256 glyphs. When stale screen data with high bits
remains after a font switch, or when vcs_write() stores an arbitrary
value, clamping the index to 0 prevents the out-of-bounds read without
changing cursor semantics — the same fallback bit_putcs uses.
🎖@cveNotify
🚨 CVE-2026-74636
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix race between update_event_fields and, event_define_fields
The following sequence may leads race between event_define_fields()
and update_event_fields():
CPU0 (loads module A) CPU1 (loads module B)
=============================== ===============================
load_module(A) load_module(B)
notifier_call_chain notifier_call_chain
trace_module_notify trace_module_notify
mutex_lock(&event_mutex) trace_event_update_all()
trace_module_add_events(A) down_write(&trace_event_sem)
__register_event(call_A)
__add_event_to_tracers(call_A)
event_define_fields(call_A)
for each f: list_for_each_entry(field,
list_add(&f->link, &class->fields, link)
&class->fields) field = class->fields->next;
Where access to the class->fields is not protected by the event_mutex in
trace_event_update_all().
This produces the following panic:
Unable to handle kernel access ... at virtual address 0000000000000018
pc : update_event_fields+0xf8/0x368
Call trace:
update_event_fields+0xf8/0x368
trace_event_update_all+0x7c/0x2b4
trace_module_notify+0x4c/0x1dc
notifier_call_chain+0x84/0x168
blocking_notifier_call_chain_robust+0x64/0xd4
load_module+0x10c8/0x123c
__arm64_sys_finit_module+0x230/0x31c
Fix by taking event_mutex in trace_event_update_all() before
trace_event_sem.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix race between update_event_fields and, event_define_fields
The following sequence may leads race between event_define_fields()
and update_event_fields():
CPU0 (loads module A) CPU1 (loads module B)
=============================== ===============================
load_module(A) load_module(B)
notifier_call_chain notifier_call_chain
trace_module_notify trace_module_notify
mutex_lock(&event_mutex) trace_event_update_all()
trace_module_add_events(A) down_write(&trace_event_sem)
__register_event(call_A)
__add_event_to_tracers(call_A)
event_define_fields(call_A)
for each f: list_for_each_entry(field,
list_add(&f->link, &class->fields, link)
&class->fields) field = class->fields->next;
Where access to the class->fields is not protected by the event_mutex in
trace_event_update_all().
This produces the following panic:
Unable to handle kernel access ... at virtual address 0000000000000018
pc : update_event_fields+0xf8/0x368
Call trace:
update_event_fields+0xf8/0x368
trace_event_update_all+0x7c/0x2b4
trace_module_notify+0x4c/0x1dc
notifier_call_chain+0x84/0x168
blocking_notifier_call_chain_robust+0x64/0xd4
load_module+0x10c8/0x123c
__arm64_sys_finit_module+0x230/0x31c
Fix by taking event_mutex in trace_event_update_all() before
trace_event_sem.
🎖@cveNotify
🚨 CVE-2026-74637
In the Linux kernel, the following vulnerability has been resolved:
perf/core: Fix group leader use-after-free after sibling detach
perf_group_detach() handles leader and sibling detach differently. When the
group leader is detached, all siblings are promoted to singleton events and
their group_leader pointer is reset to themselves. When a sibling is
detached, it is removed from the leader's sibling_list, but its
group_leader pointer is left pointing at the old leader.
That is harmless when the sibling is being closed and freed immediately, as
in the DETACH_DEAD path. It is not safe when the sibling is detached but
kept alive, such as during CPU hotplug with DETACH_GROUP. In that case the
sibling is removed from the context, while its file descriptor can still
keep it alive.
A typical failing sequence is:
- A group contains leader L and sibling S.
- CPU hot-unplug detaches S with DETACH_GROUP, removing it from
L->sibling_list but leaving S->group_leader == L.
- L is later closed and freed.
- A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and
dereferences the freed leader.
This was reproduced by running the perf event fuzzer, CPU hotplug, and a
stress workload concurrently:
Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb
CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT
pc : perf_ioctl+0x34c/0xc68
x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b
Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)
Call trace:
perf_ioctl+0x34c/0xc68 (P)
__arm64_sys_ioctl+0xa0/0xf4
invoke_syscall+0x58/0xe4
el0_svc_common+0xa8/0xdc
do_el0_svc+0x1c/0x28
el0_svc+0x40/0xc0
el0t_64_sync_handler+0x68/0xdc
el0t_64_sync+0x1c4/0x1c8
The fault happened in perf_ioctl(), where perf_event_for_each() follows
the stale group_leader pointer and perf_event_for_each_child() then
dereferences the freed leader's context.
Fix the use-after-free by promoting the detached sibling to a singleton.
Also fix __event_disable() cgroup accounting and event state change.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
perf/core: Fix group leader use-after-free after sibling detach
perf_group_detach() handles leader and sibling detach differently. When the
group leader is detached, all siblings are promoted to singleton events and
their group_leader pointer is reset to themselves. When a sibling is
detached, it is removed from the leader's sibling_list, but its
group_leader pointer is left pointing at the old leader.
That is harmless when the sibling is being closed and freed immediately, as
in the DETACH_DEAD path. It is not safe when the sibling is detached but
kept alive, such as during CPU hotplug with DETACH_GROUP. In that case the
sibling is removed from the context, while its file descriptor can still
keep it alive.
A typical failing sequence is:
- A group contains leader L and sibling S.
- CPU hot-unplug detaches S with DETACH_GROUP, removing it from
L->sibling_list but leaving S->group_leader == L.
- L is later closed and freed.
- A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and
dereferences the freed leader.
This was reproduced by running the perf event fuzzer, CPU hotplug, and a
stress workload concurrently:
Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb
CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT
pc : perf_ioctl+0x34c/0xc68
x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b
Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)
Call trace:
perf_ioctl+0x34c/0xc68 (P)
__arm64_sys_ioctl+0xa0/0xf4
invoke_syscall+0x58/0xe4
el0_svc_common+0xa8/0xdc
do_el0_svc+0x1c/0x28
el0_svc+0x40/0xc0
el0t_64_sync_handler+0x68/0xdc
el0t_64_sync+0x1c4/0x1c8
The fault happened in perf_ioctl(), where perf_event_for_each() follows
the stale group_leader pointer and perf_event_for_each_child() then
dereferences the freed leader's context.
Fix the use-after-free by promoting the detached sibling to a singleton.
Also fix __event_disable() cgroup accounting and event state change.
🎖@cveNotify
🚨 CVE-2026-74638
In the Linux kernel, the following vulnerability has been resolved:
drm/v3d: Serialize the scheduler timeout handlers
V3D exposes several independent hardware queues (BIN, RENDER, TFU and
CSD) but has only a single, global reset. A timeout on any one queue
therefore has to stop, reset and restart the schedulers of every other
queue as well. That makes concurrent timeout handlers unsafe.
`reset_lock` was never able to make them safe, as a driver-side lock can
only cover the driver's &drm_sched_backend_ops.timedout_job callback.
The scheduler handles the timed out job and its pending list around that
callback, outside of the driver's control, so a global reset triggered
by one queue can still interfere with another queue that is in the
middle of handling a timeout of its own.
Consequently, if a reset happens in the CSD queue while a CL-intensive
application is running, the global reset stops and restarts the CL
queue's scheduler while that queue is handling a timeout of its own. As
drm_sched_stop() and drm_sched_start() subtract and add the credits of
every job sitting on the pending list of the scheduler they are called
on, and as the CL queue's handler concurrently takes its job off that
same list and puts it back, the stop and the start no longer see the
same set of jobs. The CL queue is left with more credits in flight than
its limit:
[ 327.302739] ------------[ cut here ]------------
[ 327.302744] WARNING: CPU: 2 PID: 43 at drivers/gpu/drm/scheduler/sched_main.c:102 drm_sched_run_job_work+0x238/0x4d0 [gpu_sched]
[ 327.302884] CPU: 2 UID: 0 PID: 43 Comm: kworker/u16:1 Not tainted 6.18.39-v8-16k+ #3 PREEMPT
[ 327.302889] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT)
[ 327.302893] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched]
[ 327.302984] Call trace:
[ 327.302987] drm_sched_run_job_work+0x238/0x4d0 [gpu_sched] (P)
[ 327.302997] process_scheduled_works+0x180/0x3d0
[ 327.303010] worker_thread+0x268/0x3e8
[ 327.303016] kthread+0x140/0x250
[ 327.303022] ret_from_fork+0x10/0x20
[ 327.303031] ---[ end trace 0000000000000000 ]---
From that point on, the credit count of the CL queue is broken, causing
a complete GPU hang and UI freeze.
The DRM scheduler already provides a mechanism to serialize the timeout
handlers of different schedulers: an ordered workqueue passed as
drm_sched_init()'s @timeout_wq parameter. By default, each scheduler
queues its timeout work on the system workqueue, which runs the handlers
concurrently. Give all of the queues a shared ordered workqueue instead,
as recommended by the DRM scheduler documentation for hardware that has
distinct queues but resets globally.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
drm/v3d: Serialize the scheduler timeout handlers
V3D exposes several independent hardware queues (BIN, RENDER, TFU and
CSD) but has only a single, global reset. A timeout on any one queue
therefore has to stop, reset and restart the schedulers of every other
queue as well. That makes concurrent timeout handlers unsafe.
`reset_lock` was never able to make them safe, as a driver-side lock can
only cover the driver's &drm_sched_backend_ops.timedout_job callback.
The scheduler handles the timed out job and its pending list around that
callback, outside of the driver's control, so a global reset triggered
by one queue can still interfere with another queue that is in the
middle of handling a timeout of its own.
Consequently, if a reset happens in the CSD queue while a CL-intensive
application is running, the global reset stops and restarts the CL
queue's scheduler while that queue is handling a timeout of its own. As
drm_sched_stop() and drm_sched_start() subtract and add the credits of
every job sitting on the pending list of the scheduler they are called
on, and as the CL queue's handler concurrently takes its job off that
same list and puts it back, the stop and the start no longer see the
same set of jobs. The CL queue is left with more credits in flight than
its limit:
[ 327.302739] ------------[ cut here ]------------
[ 327.302744] WARNING: CPU: 2 PID: 43 at drivers/gpu/drm/scheduler/sched_main.c:102 drm_sched_run_job_work+0x238/0x4d0 [gpu_sched]
[ 327.302884] CPU: 2 UID: 0 PID: 43 Comm: kworker/u16:1 Not tainted 6.18.39-v8-16k+ #3 PREEMPT
[ 327.302889] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT)
[ 327.302893] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched]
[ 327.302984] Call trace:
[ 327.302987] drm_sched_run_job_work+0x238/0x4d0 [gpu_sched] (P)
[ 327.302997] process_scheduled_works+0x180/0x3d0
[ 327.303010] worker_thread+0x268/0x3e8
[ 327.303016] kthread+0x140/0x250
[ 327.303022] ret_from_fork+0x10/0x20
[ 327.303031] ---[ end trace 0000000000000000 ]---
From that point on, the credit count of the CL queue is broken, causing
a complete GPU hang and UI freeze.
The DRM scheduler already provides a mechanism to serialize the timeout
handlers of different schedulers: an ordered workqueue passed as
drm_sched_init()'s @timeout_wq parameter. By default, each scheduler
queues its timeout work on the system workqueue, which runs the handlers
concurrently. Give all of the queues a shared ordered workqueue instead,
as recommended by the DRM scheduler documentation for hardware that has
distinct queues but resets globally.
🎖@cveNotify
🚨 CVE-2026-74639
In the Linux kernel, the following vulnerability has been resolved:
ALSA: us144mkii: re-anchor capture URBs on resubmission
capture_urb_complete() resubmits each capture URB without anchoring it:
usb_get_urb(urb);
ret = usb_submit_urb(urb, GFP_ATOMIC);
Anchoring is a property of a submission, not of the URB. The giveback
path calls usb_unanchor_urb() before urb->complete(), so an URB
resubmitted from its own completion handler is off the anchor. The
capture URBs are anchored once, at stream start, so from the first
completion onward tascam->capture_anchor is empty.
tascam_free_urbs(), tascam_disconnect(), tascam_suspend() and the
stop-work path all call usb_kill_anchored_urbs(&tascam->capture_anchor)
to reap the capture URBs before anything is freed. With the anchor empty
those calls return immediately and the URBs stay queued on the host
controller.
tascam_free_urbs() then returns the capture transfer buffers with
usb_free_coherent(), and snd_card_free() releases the snd_card
allocation that embeds tascam (card->private_data). The controller
completes the queued URBs afterwards, writing device-supplied data into
the freed transfer buffer, and capture_urb_complete() dereferences the
freed driver object.
KASAN on 7.2.0-rc5 (arm64):
BUG: KASAN: slab-use-after-free in dummy_timer
Write of size 512 at addr ffff000015b62000
__asan_memcpy
dummy_timer
hrtimer_run_softirq
Allocated by task 64:
usb_alloc_coherent
tascam_alloc_urbs
tascam_probe
Freed by task 170:
usb_free_coherent
tascam_free_urbs
tascam_disconnect
usb_unbind_interface
BUG: KASAN: slab-use-after-free in capture_urb_complete
Read of size 4 at addr ffff0000170ee878
Freed by task 170:
release_card_device
snd_card_free
tascam_disconnect
Restore the usb_anchor_urb() between the reference count bump and the
resubmission. That also makes the handler's usb_unanchor_urb() failure
arm meaningful again and restores usb_kill_anchored_urbs() as a barrier
on the disconnect, suspend and stop-work paths.
The anchoring was removed on the premise that the URB is already anchored
from the initial submission, which does not hold once the first giveback
has run.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: us144mkii: re-anchor capture URBs on resubmission
capture_urb_complete() resubmits each capture URB without anchoring it:
usb_get_urb(urb);
ret = usb_submit_urb(urb, GFP_ATOMIC);
Anchoring is a property of a submission, not of the URB. The giveback
path calls usb_unanchor_urb() before urb->complete(), so an URB
resubmitted from its own completion handler is off the anchor. The
capture URBs are anchored once, at stream start, so from the first
completion onward tascam->capture_anchor is empty.
tascam_free_urbs(), tascam_disconnect(), tascam_suspend() and the
stop-work path all call usb_kill_anchored_urbs(&tascam->capture_anchor)
to reap the capture URBs before anything is freed. With the anchor empty
those calls return immediately and the URBs stay queued on the host
controller.
tascam_free_urbs() then returns the capture transfer buffers with
usb_free_coherent(), and snd_card_free() releases the snd_card
allocation that embeds tascam (card->private_data). The controller
completes the queued URBs afterwards, writing device-supplied data into
the freed transfer buffer, and capture_urb_complete() dereferences the
freed driver object.
KASAN on 7.2.0-rc5 (arm64):
BUG: KASAN: slab-use-after-free in dummy_timer
Write of size 512 at addr ffff000015b62000
__asan_memcpy
dummy_timer
hrtimer_run_softirq
Allocated by task 64:
usb_alloc_coherent
tascam_alloc_urbs
tascam_probe
Freed by task 170:
usb_free_coherent
tascam_free_urbs
tascam_disconnect
usb_unbind_interface
BUG: KASAN: slab-use-after-free in capture_urb_complete
Read of size 4 at addr ffff0000170ee878
Freed by task 170:
release_card_device
snd_card_free
tascam_disconnect
Restore the usb_anchor_urb() between the reference count bump and the
resubmission. That also makes the handler's usb_unanchor_urb() failure
arm meaningful again and restores usb_kill_anchored_urbs() as a barrier
on the disconnect, suspend and stop-work paths.
The anchoring was removed on the premise that the URB is already anchored
from the initial submission, which does not hold once the first giveback
has run.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74640
In the Linux kernel, the following vulnerability has been resolved:
ALSA: FCP: fix OOB write in fcp_meter_ctl_get()
fcp_ioctl_set_meter_map() bounds the user-supplied Level Meter map size
by the driver's own limit of 255
if (map.map_size < 1 || map.map_size > 255 ||
map.meter_slots < 1 || map.meter_slots > 255)
return -EINVAL;
and passes it to fcp_add_new_ctl() as the control's channel count, where
it is stored as elem->channels.
Every control read writes into struct snd_ctl_elem_value, whose integer
array is declared long value[128], so the limit is 128, not 255.
fcp_meter_ctl_get() stores one 64-bit word per channel into that array
with no bound of its own:
for (i = 0; i < elem->channels; i++) {
int idx = private->meter_level_map[i];
int value = idx < 0 ? 0 : le32_to_cpu(resp[idx]);
ucontrol->value.integer.value[i] = value;
}
snd_ctl_elem_read_user() serves that object from
memdup_user(_control, sizeof(*control)), 1224 bytes on LP64 out of
kmalloc-2048. offsetof(struct snd_ctl_elem_value, value) is 72, so
element i is written at byte 72 + 8 * i and element 144 already lands
past the allocation. At map_size 255 the last store ends at byte 2112,
888 bytes past the object and 64 bytes into the adjacent slab object.
The stored words come from the device and meter_level_map[] selects
which word lands in which slot, so extent and contents are both
controlled.
The core does not catch this. snd_ctl_check_elem_info() is reached only
from __snd_ctl_elem_info(), which snd_ctl_elem_read() calls under
CONFIG_SND_CTL_DEBUG; without that option snd_ctl_skip_validation() is a
compile-time true. __snd_ctl_add_replace() validates kcontrol->count and
never inspects elem->channels.
Installing an oversized map needs CAP_SYS_RAWIO, but the control outlives
the hwdep descriptor that created it, so the out-of-bounds stores are
issued by any process able to read controls on /dev/snd/controlC0.
KASAN on 7.2.0-rc5 (arm64), triggered by an unprivileged control read:
BUG: KASAN: slab-out-of-bounds in fcp_meter_ctl_get
Write of size 8 at addr ffff000017af04c8 by task fcp_trigger/185
__asan_store8
fcp_meter_ctl_get
snd_ctl_elem_read
snd_ctl_ioctl
Allocated by task 185:
memdup_user
snd_ctl_ioctl
The buggy address is located 0 bytes to the right of
allocated 1224-byte region [ffff000017af0000, ffff000017af04c8)
Bound the map size by the ABI limit rather than by 255, and bound the
store loop at the sink so it cannot run past the value array whatever
elem->channels holds.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: FCP: fix OOB write in fcp_meter_ctl_get()
fcp_ioctl_set_meter_map() bounds the user-supplied Level Meter map size
by the driver's own limit of 255
if (map.map_size < 1 || map.map_size > 255 ||
map.meter_slots < 1 || map.meter_slots > 255)
return -EINVAL;
and passes it to fcp_add_new_ctl() as the control's channel count, where
it is stored as elem->channels.
Every control read writes into struct snd_ctl_elem_value, whose integer
array is declared long value[128], so the limit is 128, not 255.
fcp_meter_ctl_get() stores one 64-bit word per channel into that array
with no bound of its own:
for (i = 0; i < elem->channels; i++) {
int idx = private->meter_level_map[i];
int value = idx < 0 ? 0 : le32_to_cpu(resp[idx]);
ucontrol->value.integer.value[i] = value;
}
snd_ctl_elem_read_user() serves that object from
memdup_user(_control, sizeof(*control)), 1224 bytes on LP64 out of
kmalloc-2048. offsetof(struct snd_ctl_elem_value, value) is 72, so
element i is written at byte 72 + 8 * i and element 144 already lands
past the allocation. At map_size 255 the last store ends at byte 2112,
888 bytes past the object and 64 bytes into the adjacent slab object.
The stored words come from the device and meter_level_map[] selects
which word lands in which slot, so extent and contents are both
controlled.
The core does not catch this. snd_ctl_check_elem_info() is reached only
from __snd_ctl_elem_info(), which snd_ctl_elem_read() calls under
CONFIG_SND_CTL_DEBUG; without that option snd_ctl_skip_validation() is a
compile-time true. __snd_ctl_add_replace() validates kcontrol->count and
never inspects elem->channels.
Installing an oversized map needs CAP_SYS_RAWIO, but the control outlives
the hwdep descriptor that created it, so the out-of-bounds stores are
issued by any process able to read controls on /dev/snd/controlC0.
KASAN on 7.2.0-rc5 (arm64), triggered by an unprivileged control read:
BUG: KASAN: slab-out-of-bounds in fcp_meter_ctl_get
Write of size 8 at addr ffff000017af04c8 by task fcp_trigger/185
__asan_store8
fcp_meter_ctl_get
snd_ctl_elem_read
snd_ctl_ioctl
Allocated by task 185:
memdup_user
snd_ctl_ioctl
The buggy address is located 0 bytes to the right of
allocated 1224-byte region [ffff000017af0000, ffff000017af04c8)
Bound the map size by the ABI limit rather than by 255, and bound the
store loop at the sink so it cannot run past the value array whatever
elem->channels holds.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74641
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usx2y: bound the hwdep mmap fault offset
snd_us428ctls_vm_fault() turns the faulting page offset into a kernel
address with no bound of any kind:
offset = vmf->pgoff << PAGE_SHIFT;
vaddr = (char *)(...)->us428ctls_sharedmem + offset;
page = virt_to_page(vaddr);
get_page(page);
vmf->page = page;
return 0;
snd_us428ctls_mmap() checks only the length of the mapping, never the
offset, and us428ctls_sharedmem is a single page from
alloc_pages_exact(). For a character device file_mmap_size_max()
returns ULONG_MAX, so the mm layer imposes no ceiling either. Every page
offset above zero resolves to a struct page outside the object, and the
handler installs it into the caller's address space read-write; the vma
is not marked read-only.
The caller picks the page frame with a single mmap() argument and gets
read-write access to a page of kernel memory it does not own; an offset
that lands in an unpopulated vmemmap region oopses instead.
A process that can open the hwdep node of an attached US-X2Y reaches
this after loading the FPGA image through the same node; no capability
check is involved.
On 7.2.0-rc5 (arm64), mmap() with a large offset:
Unable to handle kernel paging request at virtual address fffffdffc45d5ac8
pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
Call trace:
snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
__do_fault
__handle_mm_fault
handle_mm_fault
el0_da
Reject any offset outside the shared region. The pcm hwdep handler in
usx2yhwdeppcm.c computes its address the same way and needs the same
bound.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usx2y: bound the hwdep mmap fault offset
snd_us428ctls_vm_fault() turns the faulting page offset into a kernel
address with no bound of any kind:
offset = vmf->pgoff << PAGE_SHIFT;
vaddr = (char *)(...)->us428ctls_sharedmem + offset;
page = virt_to_page(vaddr);
get_page(page);
vmf->page = page;
return 0;
snd_us428ctls_mmap() checks only the length of the mapping, never the
offset, and us428ctls_sharedmem is a single page from
alloc_pages_exact(). For a character device file_mmap_size_max()
returns ULONG_MAX, so the mm layer imposes no ceiling either. Every page
offset above zero resolves to a struct page outside the object, and the
handler installs it into the caller's address space read-write; the vma
is not marked read-only.
The caller picks the page frame with a single mmap() argument and gets
read-write access to a page of kernel memory it does not own; an offset
that lands in an unpopulated vmemmap region oopses instead.
A process that can open the hwdep node of an attached US-X2Y reaches
this after loading the FPGA image through the same node; no capability
check is involved.
On 7.2.0-rc5 (arm64), mmap() with a large offset:
Unable to handle kernel paging request at virtual address fffffdffc45d5ac8
pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
Call trace:
snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
__do_fault
__handle_mm_fault
handle_mm_fault
el0_da
Reject any offset outside the shared region. The pcm hwdep handler in
usx2yhwdeppcm.c computes its address the same way and needs the same
bound.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74642
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb: Fix UAF at delayed release of MIDI2 EPs
The recent fix for UAF in ump_to_endpoint() caused another UAF because
it tries to dereference the UMP endpoint object, but this might be
executed at a delayed context where the endpoint has been already
released.
Add private_free to clear the associated data for avoiding the further
dereference for delayed releases.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb: Fix UAF at delayed release of MIDI2 EPs
The recent fix for UAF in ump_to_endpoint() caused another UAF because
it tries to dereference the UMP endpoint object, but this might be
executed at a delayed context where the endpoint has been already
released.
Add private_free to clear the associated data for avoiding the further
dereference for delayed releases.
🎖@cveNotify
🚨 CVE-2026-74643
In the Linux kernel, the following vulnerability has been resolved:
samples/damon/mtier: error out for zero quota goal target values
Patch series "mm/damon: avoid division by zero from damos_quota_score()".
DAMON_SAMPLE_MTIER and DAMON_LRU_SORT allow the user to trigger division
by zero in damos_quota_score(). Avoid it by adding parameters validation
checks.
This patch (of 2):
damos_quota_score() can trigger division by zero if the target_value is
zero. DAMON_SAMPLE_MTIER lets users set the target_value via
node0_mem_{used,free}_bp parameters. It doesn't guard zero value case,
though. As a result, users can trigger division by zero. Fix the issue
by returning an error when the user tries to start DAMON with zero
node0_mem_{used,free}_bp parameter values.
DAMON_SAMPLE_MTIER is just a sample module, but the consequence is quite
bad. Also the zero node0_mem_free_bp parameter might look like a
reasonable setup to some users. Hence, the issue might really happen in
the real world.
One reliable way to reproduce the issue is like below:
# cd /sys/module/damon_sample_mtier/parameters
# echo 4096 > node0_start_addr
# echo 8192 > node0_end_addr
# echo 8192 > node1_start_addr
# echo 81920 > node1_end_addr
# echo 0 > node0_mem_free_bp
# echo Y > enabled
# dmesg -w
[...]
[18792.235916] Oops: divide error: 0000 [#1] SMP NOPTI
[...]
[18792.242787] RIP: 0010:damos_quota_score+0x6f/0x480
[...]
This issue was discovered [1] by Sashiko.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
samples/damon/mtier: error out for zero quota goal target values
Patch series "mm/damon: avoid division by zero from damos_quota_score()".
DAMON_SAMPLE_MTIER and DAMON_LRU_SORT allow the user to trigger division
by zero in damos_quota_score(). Avoid it by adding parameters validation
checks.
This patch (of 2):
damos_quota_score() can trigger division by zero if the target_value is
zero. DAMON_SAMPLE_MTIER lets users set the target_value via
node0_mem_{used,free}_bp parameters. It doesn't guard zero value case,
though. As a result, users can trigger division by zero. Fix the issue
by returning an error when the user tries to start DAMON with zero
node0_mem_{used,free}_bp parameter values.
DAMON_SAMPLE_MTIER is just a sample module, but the consequence is quite
bad. Also the zero node0_mem_free_bp parameter might look like a
reasonable setup to some users. Hence, the issue might really happen in
the real world.
One reliable way to reproduce the issue is like below:
# cd /sys/module/damon_sample_mtier/parameters
# echo 4096 > node0_start_addr
# echo 8192 > node0_end_addr
# echo 8192 > node1_start_addr
# echo 81920 > node1_end_addr
# echo 0 > node0_mem_free_bp
# echo Y > enabled
# dmesg -w
[...]
[18792.235916] Oops: divide error: 0000 [#1] SMP NOPTI
[...]
[18792.242787] RIP: 0010:damos_quota_score+0x6f/0x480
[...]
This issue was discovered [1] by Sashiko.
🎖@cveNotify