🚨 CVE-2026-74483
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: don't leak the user namespace when the mount fails
bm_get_tree() takes a reference to the user namespace and hands it to
get_tree_keyed() as the sget key. sget_fc() moves that reference into
sb->s_fs_info and clears fc->s_fs_info, so from that point on the
superblock owns it and bm_free() doesn't see it anymore.
The superblock drops it in ->put_super(). But generic_shutdown_super()
only calls ->put_super() from inside the if (sb->s_root) branch, so
nothing releases it when bm_fill_super() fails:
- The kzalloc_obj() failure leaves s_root NULL and the whole branch is
skipped.
- A simple_fill_super() failure in the file loop leaves s_root set, but
s_op still points at simple_super_operations, which has no
->put_super(). bm_fill_super() installs s_ops only once
simple_fill_super() returned success, and installing it earlier
wouldn't help either because simple_fill_super() overwrites s_op.
Either way vfs_get_super() calls deactivate_locked_super() and the
reference is gone for good. binfmt_misc mounts are available in a user
namespace and both the inode and the dentry cache are SLAB_ACCOUNT, so
an unprivileged caller under a tight memory cgroup can fail
simple_fill_super() on demand and leak one user namespace per attempt.
Drop the reference in ->kill_sb() instead, which runs unconditionally,
the same way nfsd and rpc_pipefs release their keyed s_fs_info.
That also stops ->put_super() from clearing s_fs_info while the
superblock is still on @fs_supers. generic_shutdown_super() leaves it
there on purpose so that sget_fc() keeps finding it until kill_sb() has
run, but a NULL s_fs_info makes test_keyed_super() miss it, so a
concurrent mount for the same user namespace skips the grab_super()
wait and creates a second superblock for a namespace that is still
being torn down.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: don't leak the user namespace when the mount fails
bm_get_tree() takes a reference to the user namespace and hands it to
get_tree_keyed() as the sget key. sget_fc() moves that reference into
sb->s_fs_info and clears fc->s_fs_info, so from that point on the
superblock owns it and bm_free() doesn't see it anymore.
The superblock drops it in ->put_super(). But generic_shutdown_super()
only calls ->put_super() from inside the if (sb->s_root) branch, so
nothing releases it when bm_fill_super() fails:
- The kzalloc_obj() failure leaves s_root NULL and the whole branch is
skipped.
- A simple_fill_super() failure in the file loop leaves s_root set, but
s_op still points at simple_super_operations, which has no
->put_super(). bm_fill_super() installs s_ops only once
simple_fill_super() returned success, and installing it earlier
wouldn't help either because simple_fill_super() overwrites s_op.
Either way vfs_get_super() calls deactivate_locked_super() and the
reference is gone for good. binfmt_misc mounts are available in a user
namespace and both the inode and the dentry cache are SLAB_ACCOUNT, so
an unprivileged caller under a tight memory cgroup can fail
simple_fill_super() on demand and leak one user namespace per attempt.
Drop the reference in ->kill_sb() instead, which runs unconditionally,
the same way nfsd and rpc_pipefs release their keyed s_fs_info.
That also stops ->put_super() from clearing s_fs_info while the
superblock is still on @fs_supers. generic_shutdown_super() leaves it
there on purpose so that sget_fc() keeps finding it until kill_sb() has
run, but a NULL s_fs_info makes test_keyed_super() miss it, so a
concurrent mount for the same user namespace skips the grab_super()
wait and creates a second superblock for a namespace that is still
being torn down.
🎖@cveNotify
🚨 CVE-2026-74484
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: don't let an 'F' entry pin its own instance
An entry registered with 'F' opens its interpreter at registration time
and holds that file until the entry is freed. Any entry nobody removes
by hand only gets closed once the binfmt_misc superblock is shut down.
If the interpreter lives on a mount that keeps that superblock alive the
two pin each other:
binfmt_misc sb -> inode -> entry -> interp_file -> vfsmount -> binfmt_misc sb
TL;DR the file is never closed. Once the mount namespace is gone there
is nothing left to unregister through either.
There are two ways to trigger this bug:
- Point the interpreter at the instance itself. Its files are regular
files owned by the mounter and both bm_get_inode() and
simple_fill_super() leave i_op at empty_iops. So notify_change() falls
back to simple_setattr() and chmod +x works. We never set SB_I_NOEXEC
and so open_exec() accepts it.
- Use the instance as an overlayfs lower layer. The overlay superblock
holds a clone_private_mount() of every layer until it is destroyed and
that clone is in no namespace. So umount_tree() never reaches it.
That's a DoS. And it isn't only the superblock that leaks. It pins the
user namespace it was mounted in, so every iteration permanently eats
one of the caller's user namespace charges.
So let's just do the sane thing. SB_I_NOEXEC makes open_exec() fail on
the instance's own files and s_stack_depth makes overlayfs reject the
layer before it ever takes a clone. That also covers the ecryptfs and
fuse passthrough variants. What 'F' promises is unchanged.
The stable tag is narrower than the Fixes tags on purpose. Before
sandboxed mounts this needed global root against the single instance
everyone shares, and the change doesn't apply to those trees anyway.
Note that SB_I_NODEV is implicitly raised for userns mounts but raise it
explicitly here as well.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: don't let an 'F' entry pin its own instance
An entry registered with 'F' opens its interpreter at registration time
and holds that file until the entry is freed. Any entry nobody removes
by hand only gets closed once the binfmt_misc superblock is shut down.
If the interpreter lives on a mount that keeps that superblock alive the
two pin each other:
binfmt_misc sb -> inode -> entry -> interp_file -> vfsmount -> binfmt_misc sb
TL;DR the file is never closed. Once the mount namespace is gone there
is nothing left to unregister through either.
There are two ways to trigger this bug:
- Point the interpreter at the instance itself. Its files are regular
files owned by the mounter and both bm_get_inode() and
simple_fill_super() leave i_op at empty_iops. So notify_change() falls
back to simple_setattr() and chmod +x works. We never set SB_I_NOEXEC
and so open_exec() accepts it.
- Use the instance as an overlayfs lower layer. The overlay superblock
holds a clone_private_mount() of every layer until it is destroyed and
that clone is in no namespace. So umount_tree() never reaches it.
That's a DoS. And it isn't only the superblock that leaks. It pins the
user namespace it was mounted in, so every iteration permanently eats
one of the caller's user namespace charges.
So let's just do the sane thing. SB_I_NOEXEC makes open_exec() fail on
the instance's own files and s_stack_depth makes overlayfs reject the
layer before it ever takes a clone. That also covers the ecryptfs and
fuse passthrough variants. What 'F' promises is unchanged.
The stable tag is narrower than the Fixes tags on purpose. Before
sandboxed mounts this needed global root against the single instance
everyone shares, and the change doesn't apply to those trees anyway.
Note that SB_I_NODEV is implicitly raised for userns mounts but raise it
explicitly here as well.
🎖@cveNotify
🚨 CVE-2026-74485
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: reject a flag character as the field delimiter
The registration string starts with a user chosen delimiter that
separates the individual fields. So that the field parsers terminate
even on a truncated string create_entry() pads the buffer with that
same delimiter:
memset(buf + count, del, 8);
Most fields are scanned for the delimiter with strchr()/scanarg() and
happily stop on the padding. The flags field is different: instead of
scanning for the delimiter check_special_flags() consumes the flag
characters 'P', 'O', 'C' and 'F' and stops at the first byte that is
none of them, relying on the trailing delimiter to end the scan.
If the delimiter is itself a flag character the padding no longer acts
as a terminator. The scan swallows all eight padding bytes and keeps
reading past the end of the allocation until it hits a byte that is
not a flag character. For example registering
PaPEPPxPPiP
with 'P' as the delimiter (name "a", type extension, magic "x",
interpreter "i", empty flags) leaves the flag scan running off the end
of the buffer. The registration is rejected in the end because the
parser does not stop exactly at buf + count, but only after the out of
bounds read has already happened. With an unlucky allocation layout the
scan can walk into an unmapped page; under KASAN it is reported as a
slab out of bounds read. binfmt_misc mounts are available to
unprivileged users in a user namespace so the read is reachable without
privileges.
Reject a delimiter that is one of the flag characters up front. Such a
registration was always rejected anyway, only after the out of bounds
read, so no valid registration string changes meaning.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: reject a flag character as the field delimiter
The registration string starts with a user chosen delimiter that
separates the individual fields. So that the field parsers terminate
even on a truncated string create_entry() pads the buffer with that
same delimiter:
memset(buf + count, del, 8);
Most fields are scanned for the delimiter with strchr()/scanarg() and
happily stop on the padding. The flags field is different: instead of
scanning for the delimiter check_special_flags() consumes the flag
characters 'P', 'O', 'C' and 'F' and stops at the first byte that is
none of them, relying on the trailing delimiter to end the scan.
If the delimiter is itself a flag character the padding no longer acts
as a terminator. The scan swallows all eight padding bytes and keeps
reading past the end of the allocation until it hits a byte that is
not a flag character. For example registering
PaPEPPxPPiP
with 'P' as the delimiter (name "a", type extension, magic "x",
interpreter "i", empty flags) leaves the flag scan running off the end
of the buffer. The registration is rejected in the end because the
parser does not stop exactly at buf + count, but only after the out of
bounds read has already happened. With an unlucky allocation layout the
scan can walk into an unmapped page; under KASAN it is reported as a
slab out of bounds read. binfmt_misc mounts are available to
unprivileged users in a user namespace so the read is reachable without
privileges.
Reject a delimiter that is one of the flag characters up front. Such a
registration was always rejected anyway, only after the out of bounds
read, so no valid registration string changes meaning.
🎖@cveNotify
🚨 CVE-2026-74486
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: use exe_file_deny_write_access() for the interpreter clone
For MISC_FMT_OPEN_FILE entries load_misc_binary() clones the
registered interpreter file and denies write access to the clone via
plain deny_write_access(). The clone is installed as
bprm->interpreter and later released by the exec machinery through
exe_file_allow_write_access() which skips the i_writecount increment
for files with FMODE_FSNOTIFY_HSM set.
The deny and allow side can therefore come to different conclusions
when pre-content watches are in play: if a pre-content watch is added
to the interpreter after registration every subsequent exec through
that entry takes a write denial on the clone that is never paired
with a write allowance, driving the interpreter inode's i_writecount
further down with each exec and leaving the interpreter unwritable
even after the entry and all its users are gone.
Take the write denial via exe_file_deny_write_access() so both sides
of the pairing base their decision on the same file mode, and
propagate failure instead of silently ignoring it: an interpreter
that is concurrently open for writing now fails the exec with
ETXTBSY, exactly like an interpreter freshly opened via open_exec()
would.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: use exe_file_deny_write_access() for the interpreter clone
For MISC_FMT_OPEN_FILE entries load_misc_binary() clones the
registered interpreter file and denies write access to the clone via
plain deny_write_access(). The clone is installed as
bprm->interpreter and later released by the exec machinery through
exe_file_allow_write_access() which skips the i_writecount increment
for files with FMODE_FSNOTIFY_HSM set.
The deny and allow side can therefore come to different conclusions
when pre-content watches are in play: if a pre-content watch is added
to the interpreter after registration every subsequent exec through
that entry takes a write denial on the clone that is never paired
with a write allowance, driving the interpreter inode's i_writecount
further down with each exec and leaving the interpreter unwritable
even after the entry and all its users are gone.
Take the write denial via exe_file_deny_write_access() so both sides
of the pairing base their decision on the same file mode, and
propagate failure instead of silently ignoring it: an interpreter
that is concurrently open for writing now fails the exec with
ETXTBSY, exactly like an interpreter freshly opened via open_exec()
would.
🎖@cveNotify
🚨 CVE-2026-74488
In the Linux kernel, the following vulnerability has been resolved:
wifi: mwifiex: use the subframe length when parsing A-MSDU TDLS frames
mwifiex_11n_dispatch_amsdu_pkt() splits an A-MSDU with
ieee80211_amsdu_to_8023s() and walks the resulting subframes. For each
subframe it passes the subframe data pointer to
mwifiex_process_tdls_action_frame(), but pairs it with skb->len, the
length of the A-MSDU parent, instead of rx_skb->len:
rx_skb = __skb_dequeue(&list);
rx_hdr = (struct rx_packet_hdr *)rx_skb->data;
if (ISSUPP_TDLS_ENABLED(priv->adapter->fw_cap_info) &&
ntohs(rx_hdr->eth803_hdr.h_proto) == ETH_P_TDLS) {
mwifiex_process_tdls_action_frame(priv, (u8 *)rx_hdr,
skb->len);
}
The parent is not a valid description of that buffer, and may not be
valid memory at all. ieee80211_amsdu_to_8023s() ends with
if (!reuse_skb)
dev_kfree_skb(skb);
and it only sets reuse_skb when the parent is linear, is not a
head_frag, and is being consumed as the *last* subframe. So when the
parent does not qualify for reuse it has already been freed, and the
read of skb->len is a use-after-free. When it is reused, skb->len is
the length of the last subframe, applied to every earlier subframe,
which over-states the buffer whenever an earlier subframe is shorter.
The callee cannot absorb a wrong length, because it derives its own
ceiling from the value it is given. Each frame type computes
ies_len = len - sizeof(struct ethhdr) - TDLS_*_FIX_LEN;
and the element walk is then bounded entirely against that ceiling,
for (end = pos + ies_len; pos + 1 < end; pos += 2 + pos[1]) {
u8 ie_len = pos[1];
if (pos + 2 + ie_len > end)
break;
so a too-large len moves end past the end of the subframe and the walk
reads and copies beyond it. The A-MSDU layout is chosen by the sender,
which makes the difference between the last subframe and a shorter
earlier one remotely selectable. Reaching this requires TDLS support in
firmware and the TDLS ethertype on the subframe.
The other caller, mwifiex_process_rx_packet(), is correct: it passes a
pointer and a length that describe the same region of the RX buffer.
Pass rx_skb->len, the length of the subframe actually being parsed.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
wifi: mwifiex: use the subframe length when parsing A-MSDU TDLS frames
mwifiex_11n_dispatch_amsdu_pkt() splits an A-MSDU with
ieee80211_amsdu_to_8023s() and walks the resulting subframes. For each
subframe it passes the subframe data pointer to
mwifiex_process_tdls_action_frame(), but pairs it with skb->len, the
length of the A-MSDU parent, instead of rx_skb->len:
rx_skb = __skb_dequeue(&list);
rx_hdr = (struct rx_packet_hdr *)rx_skb->data;
if (ISSUPP_TDLS_ENABLED(priv->adapter->fw_cap_info) &&
ntohs(rx_hdr->eth803_hdr.h_proto) == ETH_P_TDLS) {
mwifiex_process_tdls_action_frame(priv, (u8 *)rx_hdr,
skb->len);
}
The parent is not a valid description of that buffer, and may not be
valid memory at all. ieee80211_amsdu_to_8023s() ends with
if (!reuse_skb)
dev_kfree_skb(skb);
and it only sets reuse_skb when the parent is linear, is not a
head_frag, and is being consumed as the *last* subframe. So when the
parent does not qualify for reuse it has already been freed, and the
read of skb->len is a use-after-free. When it is reused, skb->len is
the length of the last subframe, applied to every earlier subframe,
which over-states the buffer whenever an earlier subframe is shorter.
The callee cannot absorb a wrong length, because it derives its own
ceiling from the value it is given. Each frame type computes
ies_len = len - sizeof(struct ethhdr) - TDLS_*_FIX_LEN;
and the element walk is then bounded entirely against that ceiling,
for (end = pos + ies_len; pos + 1 < end; pos += 2 + pos[1]) {
u8 ie_len = pos[1];
if (pos + 2 + ie_len > end)
break;
so a too-large len moves end past the end of the subframe and the walk
reads and copies beyond it. The A-MSDU layout is chosen by the sender,
which makes the difference between the last subframe and a shorter
earlier one remotely selectable. Reaching this requires TDLS support in
firmware and the TDLS ethertype on the subframe.
The other caller, mwifiex_process_rx_packet(), is correct: it passes a
pointer and a length that describe the same region of the RX buffer.
Pass rx_skb->len, the length of the subframe actually being parsed.
🎖@cveNotify
🚨 CVE-2026-74489
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: fix tid_tx use-after-free on BA session stop
ieee80211_stop_tx_ba_cb() hands tid_tx to kfree_rcu() through
ieee80211_remove_tid_tx(), and then reads tid_tx->ndp after dropping
sta->lock:
ieee80211_remove_tid_tx(sta, tid); /* kfree_rcu(tid_tx, rcu_head) */
...
spin_unlock_bh(&sta->lock);
if (start_txq)
ieee80211_agg_start_txq(sta, tid, false);
if (send_delba)
ieee80211_send_delba(..., tid_tx->ndp);
That read is not covered by an RCU read-side critical section, and it runs
in preemptible process context: both callers hold the wiphy mutex, reaching
it either from the ieee80211_ba_session_work() wiphy work or from
ieee80211_sta_tear_down_BA_sessions() during station teardown.
Softirqs can run in that window too, both from the local_bh_enable() that
ends ieee80211_agg_start_txq() and from any interrupt exit, so the RCU
callback can free tid_tx before the read.
Driving the function from a test module with the grace period forced into
that window, KASAN reports the read, and the free arrives on the ordinary
RCU softirq path:
BUG: KASAN: slab-use-after-free in ieee80211_stop_tx_ba_cb+0x3cd/0x400
Read of size 1 at addr ffff888002b9f52e by task kworker/0:1/10
[...]
Freed by task 57:
__kasan_slab_free+0x47/0x70
__rcu_free_sheaf_prepare+0x70/0x250
rcu_free_sheaf_nobarn+0x18/0x40
rcu_core+0x426/0x1310
handle_softirqs+0x144/0x590
__irq_exit_rcu+0xea/0x150
irq_exit_rcu+0x9/0x20
sysvec_apic_timer_interrupt+0x6b/0x80
asm_sysvec_apic_timer_interrupt+0x1a/0x20
send_delba is only set when tx_stop is set, which happens for
AGG_STOP_LOCAL_REQUEST alone, so this is reached on local teardown -
session idle timeout, PTK rekey, suspend, HW reconfig - and not from a
peer's DELBA.
Read ndp into a local before the session is freed, while sta->lock is still
held. tid_tx->ndp has a single writer, in
ieee80211_tx_ba_session_handle_start(), which cannot run concurrently here:
both paths are serialised by the wiphy mutex, and the session is already
marked HT_AGG_STATE_STOPPING at this point. tid_tx->ndp is also the only
tid_tx dereference left after ieee80211_remove_tid_tx() in this function.
[move/change the comment a bit to be more general not just on ndp,
initialize ndp directly]
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: fix tid_tx use-after-free on BA session stop
ieee80211_stop_tx_ba_cb() hands tid_tx to kfree_rcu() through
ieee80211_remove_tid_tx(), and then reads tid_tx->ndp after dropping
sta->lock:
ieee80211_remove_tid_tx(sta, tid); /* kfree_rcu(tid_tx, rcu_head) */
...
spin_unlock_bh(&sta->lock);
if (start_txq)
ieee80211_agg_start_txq(sta, tid, false);
if (send_delba)
ieee80211_send_delba(..., tid_tx->ndp);
That read is not covered by an RCU read-side critical section, and it runs
in preemptible process context: both callers hold the wiphy mutex, reaching
it either from the ieee80211_ba_session_work() wiphy work or from
ieee80211_sta_tear_down_BA_sessions() during station teardown.
Softirqs can run in that window too, both from the local_bh_enable() that
ends ieee80211_agg_start_txq() and from any interrupt exit, so the RCU
callback can free tid_tx before the read.
Driving the function from a test module with the grace period forced into
that window, KASAN reports the read, and the free arrives on the ordinary
RCU softirq path:
BUG: KASAN: slab-use-after-free in ieee80211_stop_tx_ba_cb+0x3cd/0x400
Read of size 1 at addr ffff888002b9f52e by task kworker/0:1/10
[...]
Freed by task 57:
__kasan_slab_free+0x47/0x70
__rcu_free_sheaf_prepare+0x70/0x250
rcu_free_sheaf_nobarn+0x18/0x40
rcu_core+0x426/0x1310
handle_softirqs+0x144/0x590
__irq_exit_rcu+0xea/0x150
irq_exit_rcu+0x9/0x20
sysvec_apic_timer_interrupt+0x6b/0x80
asm_sysvec_apic_timer_interrupt+0x1a/0x20
send_delba is only set when tx_stop is set, which happens for
AGG_STOP_LOCAL_REQUEST alone, so this is reached on local teardown -
session idle timeout, PTK rekey, suspend, HW reconfig - and not from a
peer's DELBA.
Read ndp into a local before the session is freed, while sta->lock is still
held. tid_tx->ndp has a single writer, in
ieee80211_tx_ba_session_handle_start(), which cannot run concurrently here:
both paths are serialised by the wiphy mutex, and the session is already
marked HT_AGG_STATE_STOPPING at this point. tid_tx->ndp is also the only
tid_tx dereference left after ieee80211_remove_tid_tx() in this function.
[move/change the comment a bit to be more general not just on ndp,
initialize ndp directly]
🎖@cveNotify
🚨 CVE-2026-74490
In the Linux kernel, the following vulnerability has been resolved:
tipc: avoid use-after-free in poll trace queue dumps
TIPC socket tracepoints dump queue state through tipc_sk_dump(). Most
queue-dump callsites already serialize that walk under the socket lock or
sk->sk_lock.slock, but tipc_poll() calls trace_tipc_sk_poll(...,
TIPC_DUMP_ALL, ...) without holding either lock.
That lets the poll trace path reach tipc_list_dump() and backlog head/tail
dumping while another context dequeues and frees an skb, leaving the trace
helper dereferencing a stale queue entry.
Stop the unlocked poll trace site from requesting queue dumps. Other queue
dump trace callsites keep their existing output under the locking they
already provide, while poll still emits the event itself without walking
live queue members from an unlocked context.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
tipc: avoid use-after-free in poll trace queue dumps
TIPC socket tracepoints dump queue state through tipc_sk_dump(). Most
queue-dump callsites already serialize that walk under the socket lock or
sk->sk_lock.slock, but tipc_poll() calls trace_tipc_sk_poll(...,
TIPC_DUMP_ALL, ...) without holding either lock.
That lets the poll trace path reach tipc_list_dump() and backlog head/tail
dumping while another context dequeues and frees an skb, leaving the trace
helper dereferencing a stale queue entry.
Stop the unlocked poll trace site from requesting queue dumps. Other queue
dump trace callsites keep their existing output under the locking they
already provide, while poll still emits the event itself without walking
live queue members from an unlocked context.
🎖@cveNotify
🚨 CVE-2026-74491
In the Linux kernel, the following vulnerability has been resolved:
of/address: Fix NULL bus dereference in of_pci_range_parser_one()
The bus matching rework made of_match_bus() return NULL for nodes with
ranges/dma-ranges but no local #address-cells. parser_init() stored that
NULL bus, and the range iterator later dereferenced it.
Reject such nodes in parser_init(), leaving an explicit empty
iterator for callers that ignore the init return, and make
of_dma_get_max_cpu_address() honour the init failure so a rejected node
cannot clamp the DMA limit.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
of/address: Fix NULL bus dereference in of_pci_range_parser_one()
The bus matching rework made of_match_bus() return NULL for nodes with
ranges/dma-ranges but no local #address-cells. parser_init() stored that
NULL bus, and the range iterator later dereferenced it.
Reject such nodes in parser_init(), leaving an explicit empty
iterator for callers that ignore the init return, and make
of_dma_get_max_cpu_address() honour the init failure so a rejected node
cannot clamp the DMA limit.
🎖@cveNotify
🚨 CVE-2026-74492
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ipset: do not update comments from kernel-side hash adds
mtype_resize() copies comment pointers with memcpy(), not the comment
objects themselves. During the window after an entry has been copied but
before the table swap and backlog replay, the old table is still
published for packet-side updates while the replacement-table entry
already holds the same ip_set_comment_rcu pointer.
If xt_SET --add-set ... --exist hits that old entry in this window,
mtype_add() calls ip_set_init_comment() even though packet-side adds
carry no comment payload. That call frees the shared comment through the
old entry, so the replacement-table entry now holds a stale pointer.
When the queued add is replayed on the new table, mtype_add() calls
ip_set_init_comment() again and strlen() dereferences the stale pointer.
Fix this in mtype_add() by skipping ip_set_init_comment() when
ext->target marks a packet-side add. Userspace adds still update
comments, while packet-side adds can no longer free comment storage
shared with a resize copy.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ipset: do not update comments from kernel-side hash adds
mtype_resize() copies comment pointers with memcpy(), not the comment
objects themselves. During the window after an entry has been copied but
before the table swap and backlog replay, the old table is still
published for packet-side updates while the replacement-table entry
already holds the same ip_set_comment_rcu pointer.
If xt_SET --add-set ... --exist hits that old entry in this window,
mtype_add() calls ip_set_init_comment() even though packet-side adds
carry no comment payload. That call frees the shared comment through the
old entry, so the replacement-table entry now holds a stale pointer.
When the queued add is replayed on the new table, mtype_add() calls
ip_set_init_comment() again and strlen() dereferences the stale pointer.
Fix this in mtype_add() by skipping ip_set_init_comment() when
ext->target marks a packet-side add. Userspace adds still update
comments, while packet-side adds can no longer free comment storage
shared with a resize copy.
🎖@cveNotify
🚨 CVE-2026-74493
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix socket use-after-free during link group termination
__smc_lgr_terminate() drops conns_lock after finding a connection in
lgr->conns_all, but before taking a reference on its socket. The connection
is embedded in the socket, and its registration reference protects it only
while the connection remains in the tree.
A concurrent close can unregister the connection and drop that reference,
freeing the socket before the termination worker reaches sock_hold().
The race is reachable when close overlaps link group termination.
Local stress testing reproduced the use-after-free and KASAN reported:
BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc]
Write of size 4 by task kworker/3:3
Workqueue: events smc_lgr_terminate_work [smc]
__smc_lgr_terminate.part.0 [smc]
The socket was allocated by smc_create(), freed through
slab_free_after_rcu_debug(), and was followed by:
refcount_t: addition on 0; use-after-free.
__smc_lgr_terminate.part.0 [smc]
Take the socket reference while conns_lock still protects the tree entry.
The unregister path then cannot drop the last reference until termination
has finished using the socket.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix socket use-after-free during link group termination
__smc_lgr_terminate() drops conns_lock after finding a connection in
lgr->conns_all, but before taking a reference on its socket. The connection
is embedded in the socket, and its registration reference protects it only
while the connection remains in the tree.
A concurrent close can unregister the connection and drop that reference,
freeing the socket before the termination worker reaches sock_hold().
The race is reachable when close overlaps link group termination.
Local stress testing reproduced the use-after-free and KASAN reported:
BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc]
Write of size 4 by task kworker/3:3
Workqueue: events smc_lgr_terminate_work [smc]
__smc_lgr_terminate.part.0 [smc]
The socket was allocated by smc_create(), freed through
slab_free_after_rcu_debug(), and was followed by:
refcount_t: addition on 0; use-after-free.
__smc_lgr_terminate.part.0 [smc]
Take the socket reference while conns_lock still protects the tree entry.
The unregister path then cannot drop the last reference until termination
has finished using the socket.
🎖@cveNotify
🚨 CVE-2026-74494
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: reject repeated SMB2 NEGOTIATE requests
Unauthenticated client can send multiple successful SMB2 NEGOTIATE
requests on one connection before SESSION_SETUP. While the connection is
in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another
SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation.
Only the final allocation is freed when the connection is released, leaking
one object for every additional successful request.
A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol
violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect
without replying in this case. Set the connection exiting when rejecting
the request, in addition to suppressing the response.
Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the
SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize
both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they
update connection-wide dialect and negotiation state.
Move the locking contract to ksmbd_smb_negotiate_common(), where the state
and dialect are selected, and add ksmbd_conn_new() for consistent state
access.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: reject repeated SMB2 NEGOTIATE requests
Unauthenticated client can send multiple successful SMB2 NEGOTIATE
requests on one connection before SESSION_SETUP. While the connection is
in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another
SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation.
Only the final allocation is freed when the connection is released, leaking
one object for every additional successful request.
A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol
violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect
without replying in this case. Set the connection exiting when rejecting
the request, in addition to suppressing the response.
Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the
SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize
both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they
update connection-wide dialect and negotiation state.
Move the locking contract to ksmbd_smb_negotiate_common(), where the state
and dialect are selected, and add ksmbd_conn_new() for consistent state
access.
🎖@cveNotify
🚨 CVE-2026-74495
In the Linux kernel, the following vulnerability has been resolved:
igbvf: Fix leak in TX DMA error cleanup
If an error is encountered while mapping TX buffers, the driver should
unmap any buffers already mapped for that skb.
Because count is incremented before each frag mapping, it will always
match the correct number of unmappings needed when dma_error is reached.
Decrementing count before the while loop in dma_error causes an
off-by-one error. If any mapping was successful before an unsuccessful
mapping, exactly one DMA mapping (the head) would leak.
This bug was introduced by a 2010 fix for an endless loop in dma_error.
All other affected drivers have already been fixed.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
igbvf: Fix leak in TX DMA error cleanup
If an error is encountered while mapping TX buffers, the driver should
unmap any buffers already mapped for that skb.
Because count is incremented before each frag mapping, it will always
match the correct number of unmappings needed when dma_error is reached.
Decrementing count before the while loop in dma_error causes an
off-by-one error. If any mapping was successful before an unsuccessful
mapping, exactly one DMA mapping (the head) would leak.
This bug was introduced by a 2010 fix for an endless loop in dma_error.
All other affected drivers have already been fixed.
🎖@cveNotify
🚨 CVE-2026-74496
In the Linux kernel, the following vulnerability has been resolved:
fou: Fix use-after-free in fou_create()
fou_create() publishes struct fou through sk_user_data before adding the
new FOU port to the per-netns list. If fou_add_to_port_list() fails,
the error path frees fou while it is still reachable through
sk_user_data. A concurrent receive can then dereference the freed
object in fou_from_sock().
This ordering issue was previously noted in the linked discussion.
The failure is reachable when local port 0 is requested. Each socket
binds to a different ephemeral port, but fou_cfg_cmp() compares the
requested port 0 and reports -EALREADY once an entry already exists.
Release the tunnel socket before freeing fou so sk_user_data is cleared
first, and defer reclamation with kfree_rcu() to protect concurrent RCU
readers. This matches the lifetime handling in fou_release().
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
fou: Fix use-after-free in fou_create()
fou_create() publishes struct fou through sk_user_data before adding the
new FOU port to the per-netns list. If fou_add_to_port_list() fails,
the error path frees fou while it is still reachable through
sk_user_data. A concurrent receive can then dereference the freed
object in fou_from_sock().
This ordering issue was previously noted in the linked discussion.
The failure is reachable when local port 0 is requested. Each socket
binds to a different ephemeral port, but fou_cfg_cmp() compares the
requested port 0 and reports -EALREADY once an entry already exists.
Release the tunnel socket before freeing fou so sk_user_data is cleared
first, and defer reclamation with kfree_rcu() to protect concurrent RCU
readers. This matches the lifetime handling in fou_release().
🎖@cveNotify
🚨 CVE-2026-74497
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: Clamp frame size in implicit-feedback mode
snd_usb_handle_sync_urb() scales received sync packet sizes by the sender's
stride and stores the result directly in out_packet->packet_size[i]. If a
connected USB device sends an oversized sync packet, this frame count can
exceed ep->maxframesize.
The un-clamped frame count then propagates to the playback endpoint queue,
potentially driving packet transfers beyond the endpoint's hardware frame
limits.
Cap the calculated frame count against ep->maxframesize in
snd_usb_handle_sync_urb() to prevent oversized packets from entering the
playback queue.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: Clamp frame size in implicit-feedback mode
snd_usb_handle_sync_urb() scales received sync packet sizes by the sender's
stride and stores the result directly in out_packet->packet_size[i]. If a
connected USB device sends an oversized sync packet, this frame count can
exceed ep->maxframesize.
The un-clamped frame count then propagates to the playback endpoint queue,
potentially driving packet transfers beyond the endpoint's hardware frame
limits.
Cap the calculated frame count against ep->maxframesize in
snd_usb_handle_sync_urb() to prevent oversized packets from entering the
playback queue.
🎖@cveNotify
🚨 CVE-2026-74498
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: Fix DMA buffer out-of-bounds write when fill_max is set
When a USB audio endpoint requests full packet transfers via the fill_max
descriptor flag, data_ep_set_params() promotes ep->curpacksize to
ep->maxpacksize. However, maxsize is left at the original sample-rate
derived value.
Since u->buffer_size is allocated as maxsize * packets, the resulting
DMA buffer is far too small for the requested transfer length. When the
USB host controller streams up to curpacksize bytes per packet, it writes
past the end of the buffer via DMA, corrupting kernel heap memory.
Update maxsize to curpacksize when fill_max is set so that the allocated
DMA buffer size matches the actual transfer request size.
[ changed to reassign maxsize only when ep->fill_max is set -- tiwai ]
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: Fix DMA buffer out-of-bounds write when fill_max is set
When a USB audio endpoint requests full packet transfers via the fill_max
descriptor flag, data_ep_set_params() promotes ep->curpacksize to
ep->maxpacksize. However, maxsize is left at the original sample-rate
derived value.
Since u->buffer_size is allocated as maxsize * packets, the resulting
DMA buffer is far too small for the requested transfer length. When the
USB host controller streams up to curpacksize bytes per packet, it writes
past the end of the buffer via DMA, corrupting kernel heap memory.
Update maxsize to curpacksize when fill_max is set so that the allocated
DMA buffer size matches the actual transfer request size.
[ changed to reassign maxsize only when ep->fill_max is set -- tiwai ]
🎖@cveNotify
🚨 CVE-2026-74499
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()
snd_usbmidi_akai_output() computes its fill-loop bound
buf_end = ep->max_transfer - MAX_AKAI_SYSEX_LEN - 1;
as a signed int, so a small device-advertised bulk-OUT max_transfer
makes buf_end negative. The loop guard then compares the u32
urb->transfer_buffer_length against that negative int: the usual
arithmetic conversion turns buf_end into a large unsigned value, so the
guard stays true and each iteration keeps appending SysEx framing and
payload bytes past the end of the URB transfer buffer, which is only
max_transfer bytes long.
A USB device that advertises a tiny bulk-OUT endpoint can therefore
trigger an attacker-length- and content-controlled heap out-of-bounds
write when a process writes to the created /dev/snd/midiC*D* node.
Return early when there is no room for even one SysEx, so the loop is
never entered with a bound that would wrap. The loop is the last
statement of the function, so bailing out is equivalent to it not
running.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()
snd_usbmidi_akai_output() computes its fill-loop bound
buf_end = ep->max_transfer - MAX_AKAI_SYSEX_LEN - 1;
as a signed int, so a small device-advertised bulk-OUT max_transfer
makes buf_end negative. The loop guard then compares the u32
urb->transfer_buffer_length against that negative int: the usual
arithmetic conversion turns buf_end into a large unsigned value, so the
guard stays true and each iteration keeps appending SysEx framing and
payload bytes past the end of the URB transfer buffer, which is only
max_transfer bytes long.
A USB device that advertises a tiny bulk-OUT endpoint can therefore
trigger an attacker-length- and content-controlled heap out-of-bounds
write when a process writes to the created /dev/snd/midiC*D* node.
Return early when there is no room for even one SysEx, so the loop is
never entered with a bound that would wrap. The loop is the last
statement of the function, so bailing out is equivalent to it not
running.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74500
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix stack info leak in RME Digiface status
snd_rme_digiface_read_status() reads a four-word status block from the
device into an uninitialised on-stack __le32 buf[4] and, whenever the
vendor control-IN transfer does not return a negative error, copies all
four words into the caller's status[].
snd_usb_ctl_msg() copies the full requested size back into the caller's
buffer regardless of how many bytes the data stage actually delivered:
buf = kmemdup(data, size, GFP_KERNEL);
err = usb_control_msg(dev, pipe, request, requesttype,
value, index, buf, size, timeout);
memcpy(data, buf, size);
usb_control_msg() returns the transferred length on a short control-IN,
which is a non-negative value, and writes only that many bytes. The
remainder of the copy back is the kmemdup()ed image of the caller's
buffer, so a device answering with a short data stage leaves the
trailing words of buf[] holding leftover kernel stack. The only guard
in the caller is err < 0, so those words are stored into status[].
They then reach user space: snd_rme_digiface_get_status_val() selects a
16-bit halfword of status[] per the control's reg/mask, and the eight
Digiface status controls together expose the whole 16-byte frame to an
unprivileged reader of /dev/snd/controlC*.
Zero-initialise the buffer so a short read yields zeros instead of stack
residue. This mirrors snd_rme_get_status1(), which already clears its
output word before the same kind of vendor read.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix stack info leak in RME Digiface status
snd_rme_digiface_read_status() reads a four-word status block from the
device into an uninitialised on-stack __le32 buf[4] and, whenever the
vendor control-IN transfer does not return a negative error, copies all
four words into the caller's status[].
snd_usb_ctl_msg() copies the full requested size back into the caller's
buffer regardless of how many bytes the data stage actually delivered:
buf = kmemdup(data, size, GFP_KERNEL);
err = usb_control_msg(dev, pipe, request, requesttype,
value, index, buf, size, timeout);
memcpy(data, buf, size);
usb_control_msg() returns the transferred length on a short control-IN,
which is a non-negative value, and writes only that many bytes. The
remainder of the copy back is the kmemdup()ed image of the caller's
buffer, so a device answering with a short data stage leaves the
trailing words of buf[] holding leftover kernel stack. The only guard
in the caller is err < 0, so those words are stored into status[].
They then reach user space: snd_rme_digiface_get_status_val() selects a
16-bit halfword of status[] per the control's reg/mask, and the eight
Digiface status controls together expose the whole 16-byte frame to an
unprivileged reader of /dev/snd/controlC*.
Zero-initialise the buffer so a short read yields zeros instead of stack
residue. This mirrors snd_rme_get_status1(), which already clears its
output word before the same kind of vendor read.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74501
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix use-after-free in ump_to_endpoint()
create_midi2_ump() registers a card-owned snd_ump_endpoint and stores a
back-pointer to its per-interface snd_usb_midi2_ump object in
ump->private_data, but it never installs an ump->private_free hook and
never clears that pointer.
If a later step of snd_usb_midi_v2_create() fails, its error path calls
free_all_midi2_umps(), which kfree()s the snd_usb_midi2_ump object while
the already-registered endpoint keeps pointing at it. The created
/dev/snd/umpC*D* node stays exposed, so the first operation of any UMP
open, ump_to_endpoint(), dereferences the dangling ump->private_data and
reads rmidi->eps[dir] out of freed memory.
A malicious USB MIDI 2.0 device that makes creation fail after the
endpoint is registered can thus trigger a slab use-after-free read on a
subsequent open of the UMP node.
Clear the endpoint's back-pointer before freeing the object, and let
ump_to_endpoint() tolerate a NULL private_data so the open/close/trigger
callbacks fail cleanly (their callers already handle a NULL endpoint)
instead of dereferencing a stale pointer.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix use-after-free in ump_to_endpoint()
create_midi2_ump() registers a card-owned snd_ump_endpoint and stores a
back-pointer to its per-interface snd_usb_midi2_ump object in
ump->private_data, but it never installs an ump->private_free hook and
never clears that pointer.
If a later step of snd_usb_midi_v2_create() fails, its error path calls
free_all_midi2_umps(), which kfree()s the snd_usb_midi2_ump object while
the already-registered endpoint keeps pointing at it. The created
/dev/snd/umpC*D* node stays exposed, so the first operation of any UMP
open, ump_to_endpoint(), dereferences the dangling ump->private_data and
reads rmidi->eps[dir] out of freed memory.
A malicious USB MIDI 2.0 device that makes creation fail after the
endpoint is registered can thus trigger a slab use-after-free read on a
subsequent open of the UMP node.
Clear the endpoint's back-pointer before freeing the object, and let
ump_to_endpoint() tolerate a NULL private_data so the open/close/trigger
callbacks fail cleanly (their callers already handle a NULL endpoint)
instead of dereferencing a stale pointer.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74502
In the Linux kernel, the following vulnerability has been resolved:
ALSA: ump: fix double free of out_cvts on rawmidi error
snd_ump_attach_legacy_rawmidi() allocates the legacy conversion array
ump->out_cvts and, on the snd_rawmidi_new() error path, frees it with
kfree() but leaves ump->out_cvts pointing at the freed memory. When the
endpoint is later torn down, snd_ump_endpoint_free() frees ump->out_cvts
a second time, resulting in a double free.
The host snd-usb-audio driver attaches the legacy rawmidi for any USB
MIDI 2.0 (UMP) device, so a device that makes snd_rawmidi_new() fail
reaches this path on enumeration.
Clear ump->out_cvts after freeing it on the error path so it is not
freed again during teardown.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: ump: fix double free of out_cvts on rawmidi error
snd_ump_attach_legacy_rawmidi() allocates the legacy conversion array
ump->out_cvts and, on the snd_rawmidi_new() error path, frees it with
kfree() but leaves ump->out_cvts pointing at the freed memory. When the
endpoint is later torn down, snd_ump_endpoint_free() frees ump->out_cvts
a second time, resulting in a double free.
The host snd-usb-audio driver attaches the legacy rawmidi for any USB
MIDI 2.0 (UMP) device, so a device that makes snd_rawmidi_new() fail
reaches this path on enumeration.
Clear ump->out_cvts after freeing it on the error path so it is not
freed again during teardown.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
🎖@cveNotify
🚨 CVE-2026-74503
In the Linux kernel, the following vulnerability has been resolved:
ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes
snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD
and returns early when the flag is already set, but the flag is never
cleared again. A completed close ends in remove_slave_links(), which
leaves timeri->timer NULL, so a second close is already harmless through
the timer == NULL path; the early return can only be reached by an
instance that was opened again in between. For such an instance the
close unlinks nothing, so snd_timer_instance_free() frees an object that
is still on timer->open_list_head, still on snd_timer_master_list if it
was opened with a slave key, still owns any adopted slaves, and still
holds its timer and module references.
snd_seq_timer_open() reopens an instance exactly like that: it retries
its fallback open on the same object after a failure that has already
run snd_timer_close_locked() internally. An unprivileged user with
access to /dev/snd/timer and /dev/snd/seq can force that failure, since
snd_timer_check_master() returns -EBUSY when a pending slave matches the
new master's (slave_class, slave_id) key and the target timer has
reached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class =
SNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a
sequencer queue's key can be forged. The freed instance is afterwards
dereferenced by any further snd_timer_open() on that timer, by
snd_timer_check_slave(), and by /proc/asound/timers, which faults on the
stale ti->owner pointer.
The flag only has to be visible while the close is in progress, which is
all its other users need. Clear it in remove_slave_links(), under the
same timer->lock that sets it, once the instance is off every list.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes
snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD
and returns early when the flag is already set, but the flag is never
cleared again. A completed close ends in remove_slave_links(), which
leaves timeri->timer NULL, so a second close is already harmless through
the timer == NULL path; the early return can only be reached by an
instance that was opened again in between. For such an instance the
close unlinks nothing, so snd_timer_instance_free() frees an object that
is still on timer->open_list_head, still on snd_timer_master_list if it
was opened with a slave key, still owns any adopted slaves, and still
holds its timer and module references.
snd_seq_timer_open() reopens an instance exactly like that: it retries
its fallback open on the same object after a failure that has already
run snd_timer_close_locked() internally. An unprivileged user with
access to /dev/snd/timer and /dev/snd/seq can force that failure, since
snd_timer_check_master() returns -EBUSY when a pending slave matches the
new master's (slave_class, slave_id) key and the target timer has
reached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class =
SNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a
sequencer queue's key can be forged. The freed instance is afterwards
dereferenced by any further snd_timer_open() on that timer, by
snd_timer_check_slave(), and by /proc/asound/timers, which faults on the
stale ti->owner pointer.
The flag only has to be visible while the close is in progress, which is
all its other users need. Clear it in remove_slave_links(), under the
same timer->lock that sets it, once the instance is off every list.
🎖@cveNotify
🚨 CVE-2026-74504
In the Linux kernel, the following vulnerability has been resolved:
ALSA: seq: Fix division by zero in initialize_timer()
A userspace-driven ALSA timer (SND_UTIMER) lets an unprivileged user set
the backing snd_timer's hardware resolution to an arbitrary 64-bit value
via SNDRV_TIMER_IOCTL_CREATE. snd_utimer_create() only rejects zero.
When such a timer is bound to a sequencer queue, initialize_timer()
computes the tick period as
tmr->ticks = 1000000000 / (r * freq);
where r is that user-controlled resolution and freq is the sequencer
update rate in Hz, clamped to MIN_FREQUENCY..MAX_FREQUENCY (10..6250).
A resolution of 2^63 makes the 64-bit product r * freq wrap to zero for
any even freq, including DEFAULT_FREQUENCY (1000), so the division faults
with a divide-by-zero.
The division runs under tmr->lock with interrupts disabled, so the oops
leaves the spinlock held and hangs the CPU. It is reachable by an
unprivileged user with access to /dev/snd/timer and /dev/snd/seq.
Oops: divide error: 0000 [#1] SMP KASAN PTI
CPU: 7 UID: 1000 PID: 456 Comm: alsa_seq_utimer Not tainted 7.2.0-rc4+
RIP: 0010:initialize_timer.constprop.0+0x20a/0x2d0
snd_seq_timer_start+0x15e/0x2b0
snd_seq_control_queue+0x56f/0xba0
snd_seq_write+0x3e0/0x730
Reject an overflowing product with check_mul_overflow() and fall back to
a single tick, which also avoids feeding a wrapped-but-nonzero divisor
(e.g. 2^63 * 1000 mod 2^64 == 0, or other resolutions wrapping to a small
value) into the period computation.
🎖@cveNotify
In the Linux kernel, the following vulnerability has been resolved:
ALSA: seq: Fix division by zero in initialize_timer()
A userspace-driven ALSA timer (SND_UTIMER) lets an unprivileged user set
the backing snd_timer's hardware resolution to an arbitrary 64-bit value
via SNDRV_TIMER_IOCTL_CREATE. snd_utimer_create() only rejects zero.
When such a timer is bound to a sequencer queue, initialize_timer()
computes the tick period as
tmr->ticks = 1000000000 / (r * freq);
where r is that user-controlled resolution and freq is the sequencer
update rate in Hz, clamped to MIN_FREQUENCY..MAX_FREQUENCY (10..6250).
A resolution of 2^63 makes the 64-bit product r * freq wrap to zero for
any even freq, including DEFAULT_FREQUENCY (1000), so the division faults
with a divide-by-zero.
The division runs under tmr->lock with interrupts disabled, so the oops
leaves the spinlock held and hangs the CPU. It is reachable by an
unprivileged user with access to /dev/snd/timer and /dev/snd/seq.
Oops: divide error: 0000 [#1] SMP KASAN PTI
CPU: 7 UID: 1000 PID: 456 Comm: alsa_seq_utimer Not tainted 7.2.0-rc4+
RIP: 0010:initialize_timer.constprop.0+0x20a/0x2d0
snd_seq_timer_start+0x15e/0x2b0
snd_seq_control_queue+0x56f/0xba0
snd_seq_write+0x3e0/0x730
Reject an overflowing product with check_mul_overflow() and fall back to
a single tick, which also avoids feeding a wrapped-but-nonzero divisor
(e.g. 2^63 * 1000 mod 2^64 == 0, or other resolutions wrapping to a small
value) into the period computation.
🎖@cveNotify