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🚨 CVE-2026-68118
In the Linux kernel, the following vulnerability has been resolved:

tcp: challenge ACK for non-exact RST in SYN-RECEIVED

The SYN-RECEIVED request-socket path in tcp_check_req() accepts an
in-window RST without requiring SEG.SEQ to exactly match RCV.NXT. A
non-exact RST therefore removes the request instead of eliciting a
challenge ACK.

RFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in
SYN-RECEIVED: an exact RST resets the connection, while a non-exact
in-window RST must trigger a challenge ACK and be dropped.

Apply that check before the ACK-field validation, following the RFC
sequence-number, RST, then ACK processing order. Factor the per-netns
challenge ACK quota out of tcp_send_challenge_ack() so request sockets
can share it. Use the request socket's send_ack() callback and its own
out-of-window ACK timestamp to send and rate-limit the response.

🎖@cveNotify
🚨 CVE-2026-68119
In the Linux kernel, the following vulnerability has been resolved:

tcp: initialize standalone TCP-AO response padding

tcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP
responses with TCP-AO options. The option length carries the actual MAC
length, but the TCP header length includes the option rounded up to a
four-byte boundary.

tcp_ao_hash_hdr() writes the MAC only. Thus, when the MAC length is not
four-byte aligned, the one to three bytes after the MAC are left
uninitialized and may be transmitted. For the normal TCP-AO hashing
mode, those bytes also have to be initialized before computing the MAC.

Initialize only the alignment padding in the TCP-AO branches, before
hashing the header. Use TCPOPT_NOP, as in the normal TCP-AO output path.
This avoids adding work to non-AO TCP responses while preserving a valid
authenticated header.

🎖@cveNotify
🚨 CVE-2026-68120
In the Linux kernel, the following vulnerability has been resolved:

rtase: Workaround for TX hang caused by hardware packet parsing

The hardware performs packet parsing before packet transmission.
Parsing incomplete IPv4, IPv6, TCP, or UDP headers may trigger a TX
hang because the hardware parser expects additional protocol header
data that is not present in the packet.

The hardware performs additional PTP parsing on UDP packets identified
by destination ports 319/320 at the expected UDP destination port
offset.

If such a packet has transport data smaller than RTASE_MIN_PAD_LEN,
the hardware parser expects additional packet data and may trigger a
TX hang.

To avoid these hardware issues, the driver applies the following
workarounds.

Drop malformed packets that may trigger this hardware issue before
transmission.

For IPv4 non-initial fragments, the hardware does not check the
fragment offset before parsing the expected transport header location.
As a result, these packets are still subject to transport header
parsing even though they do not contain a transport header. If the
transport data is shorter than the minimum transport header required
by the hardware parser, pad the transport data to the minimum
transport header length required by the hardware parser. Packets that
also match the hardware PTP parsing conditions continue to follow the
corresponding workaround.

For IPv6 fragmented packets, neither of the above hardware issues
occurs because the hardware only continues packet parsing when the
IPv6 Base Header Next Header field directly indicates UDP. Packets
carrying a Fragment Header do not continue through the subsequent
packet parsing stages.

For packets identified for hardware PTP parsing, pad the transport
data so it reaches RTASE_MIN_PAD_LEN before transmission.

🎖@cveNotify
🚨 CVE-2026-68121
In the Linux kernel, the following vulnerability has been resolved:

pppoe: reload header pointer after dev_hard_header()

pppoe_sendmsg() saves a pointer to the PPPoE header before calling
dev_hard_header(). Device header callbacks are allowed to reallocate the
skb head, invalidating pointers into it.

This can happen when a send is blocked in copy_from_user() while the first
non-Ethernet port is added to an empty team device. The team's delegated
GRE header callback then expands the skb head. PPPoE subsequently writes
six bytes through the stale pointer into the freed head.

Reload the PPPoE header through the skb's network-header offset after
device header creation. pskb_expand_head() updates that offset when it
relocates the head.

🎖@cveNotify
🚨 CVE-2026-68122
In the Linux kernel, the following vulnerability has been resolved:

ovpn: fix peer refcount leak in TCP error paths

When either the TCP RX or TX error path calls ovpn_peer_hold() followed
by schedule_work(&peer->tcp.defer_del_work), and the work item is already
pending from the other path, schedule_work() returns false and the work
runs only once. Since ovpn_tcp_peer_del_work() calls ovpn_peer_put()
exactly once, the extra reference taken by the losing path is never
dropped, leaking the peer object.

The race window:

CPU0 (strparser/RX error): CPU1 (tcp_tx_work/TX error):
ovpn_peer_hold() <- refcnt+1 ovpn_peer_hold() <- refcnt+2
schedule_work() <- queued schedule_work() <- NO-OP
(work already pending)
ovpn_tcp_peer_del_work runs:
ovpn_peer_del()
ovpn_peer_put() <- refcnt+1
<- peer never freed

Fix by checking the return value of schedule_work() in both paths and
calling ovpn_peer_put() to drop the extra reference if the work was
already pending. ovpn_peer_hold() is kept unconditional in the TX path
as it cannot fail at that point.

🎖@cveNotify
🚨 CVE-2026-68123
In the Linux kernel, the following vulnerability has been resolved:

openvswitch: fix GSO userspace truncation underflow

OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb
length in OVS_CB(skb)->cutlen. When a later userspace action segments a
GSO skb, queue_gso_packets() reuses that delta for each smaller segment.
A segment can then reach queue_userspace_packet() with cutlen greater
than skb->len, underflowing the length passed to skb_zerocopy().

Store the maximum preserved length instead and bound each consumer
against the current skb length. Use U32_MAX as the no-truncation
sentinel so the value remains valid if skb geometry changes before a
consumer handles it.

🎖@cveNotify
🚨 CVE-2026-68124
In the Linux kernel, the following vulnerability has been resolved:

mctp: serial: handle zero-length frames to prevent rx buffer overflow

The MCTP serial receive state machine reads a frame length byte in
mctp_serial_push_header() case 2 and validates it upper-bound-only:

if (c > MCTP_SERIAL_FRAME_MTU) {
dev->rxstate = STATE_ERR;
} else {
dev->rxlen = c;
dev->rxpos = 0;
dev->rxstate = STATE_DATA;
...
}

A length of zero passes this check, so rxlen is set to 0 and the state
machine advances to STATE_DATA. In mctp_serial_push() STATE_DATA, the
incoming byte is stored and rxpos incremented before the terminator is

dev->rxbuf[dev->rxpos] = c;
dev->rxpos++;
dev->rxstate = STATE_DATA;
if (dev->rxpos == dev->rxlen) {
dev->rxpos = 0;
dev->rxstate = STATE_TRAILER;
}

With rxlen == 0 the "rxpos == rxlen" terminator can never fire (rxpos is
already 1 on the first data byte), so subsequent bytes are written past
the end of the fixed 74-byte rxbuf, which is the last member of the
netdev private area. Every following data byte is an attacker-controlled
1-byte out-of-bounds heap write, and the overflow continues until a
frame (0x7e) or escape byte resets the parser -- effectively unbounded.

Reaching this requires CAP_NET_ADMIN to attach the N_MCTP line
discipline and bring the resulting mctpserialN netdev up, after which
the bytes arrive via the tty receive path.

Route a zero-length frame straight to STATE_TRAILER instead of
STATE_DATA. The trailer/framing bytes are still consumed, and the frame
resolves to a zero-length skb that the MCTP core rejects; the parser
never enters STATE_DATA with rxlen == 0, so the out-of-bounds write can
no longer occur.

KASAN, on a frame of 0x7e 0x01 0x00 followed by data bytes (before this
change):

UBSAN: array-index-out-of-bounds in drivers/net/mctp/mctp-serial.c:370
index 74 is out of range for type 'u8 [74]'
BUG: KASAN: slab-out-of-bounds in mctp_serial_tty_receive_buf
Write of size 1 at addr ... by task kworker/u16:0
mctp_serial_tty_receive_buf
tty_ldisc_receive_buf
flush_to_ldisc
Allocated by task 152:
alloc_netdev_mqs
mctp_serial_open

v2: route zero-length frames to STATE_TRAILER instead of STATE_ERR so
the trailer/framing bytes are still consumed (Jeremy Kerr).

Found by 0sec automated security-research tooling (https://0sec.ai).

🎖@cveNotify
🚨 CVE-2026-68125
In the Linux kernel, the following vulnerability has been resolved:

mac802154: llsec: reject frames shorter than the authentication tag

llsec_do_decrypt_auth() computes the associated-data length for the
AEAD request as

assoclen += datalen - authlen;

where datalen is the number of bytes after the MAC header and authlen
(4, 8 or 16) is the length of the authentication tag. Nothing verifies
that the frame actually carries at least authlen payload bytes. A
secured frame whose payload is shorter than the tag makes
datalen - authlen negative; assoclen is then passed to
aead_request_set_ad() as an unsigned value close to 4 GiB, so
crypto_aead_decrypt() walks far off the end of the scatterlist that
only spans the real frame.

The frame is fully attacker-controlled and reaches this path from any
IEEE 802.15.4 peer in radio range. Reject frames whose payload is
shorter than the authentication tag before the subtraction.

Dynamically reproduced on a KASAN kernel as a general-protection-fault
in the AEAD scatterwalk, and the fix confirmed.

🎖@cveNotify
🚨 CVE-2026-68126
In the Linux kernel, the following vulnerability has been resolved:

mac802154: hold an interface reference across the scan worker

mac802154_scan_worker() captures the scanning sub-interface under RCU
and then keeps dereferencing sdata->dev after rcu_read_unlock() and
outside the rtnl -- in the failure traces, in
mac802154_transmit_beacon_req() (skb->dev = sdata->dev), and in the
end_scan cleanup. Nothing keeps that netdev alive across the worker
iteration.

A concurrent DEL_INTERFACE or PHY removal can unregister the interface
once the worker drops the rtnl between its two drv_set_channel()
sections. unregister_netdevice() frees the netdev asynchronously from
netdev_run_todo() with the rtnl already dropped, so neither holding the
rtnl nor the per-PHY IEEE802154_IS_SCANNING flag prevents a stale worker
iteration from dereferencing the freed netdev -- a KASAN
slab-use-after-free, reachable by racing TRIGGER_SCAN against
DEL_INTERFACE (both CAP_NET_ADMIN).

Pin the netdev with netdev_hold() while the RCU read lock is still held,
and release it at every worker exit.

🎖@cveNotify
🚨 CVE-2026-68127
In the Linux kernel, the following vulnerability has been resolved:

ila: reload IPv6 header after pskb_may_pull in checksum adjust

ila_csum_adjust_transport() caches ip6h = ipv6_hdr(skb) before calling
pskb_may_pull(). On a non-linear skb whose transport header sits in a page
fragment, pskb_may_pull() can call __pskb_pull_tail() / pskb_expand_head()
and free the old skb head, leaving ip6h dangling; the following
get_csum_diff(ip6h, p) then reads freed memory. ila_update_ipv6_locator()
uses ip6h (and the iaddr derived from it) again after the csum-adjust
call and additionally writes the new locator through that pointer.

Impact: a remote IPv6 packet routed through a configured ILA
csum-adjust-transport route or receive-side mapping triggers a
slab-use-after-free in ila_update_ipv6_locator() (KASAN). The route or
mapping requires CAP_NET_ADMIN to configure, but trigger packets are
unauthenticated once it exists.

Reload ip6h after each pskb_may_pull() in ila_csum_adjust_transport()
before the csum-diff read. In ila_update_ipv6_locator() only the
ILA_CSUM_ADJUST_TRANSPORT case pulls the skb, so reload ip6h and iaddr in
that case alone before the destination-address write; the neutral-map
modes never pull and keep their cached pointers.

🎖@cveNotify
🚨 CVE-2026-68128
In the Linux kernel, the following vulnerability has been resolved:

ice: reject out-of-range ptype in ice_parser_profile_init

set_bit(rslt->ptype, prof->ptypes) operates on a DECLARE_BITMAP of
ICE_FLOW_PTYPE_MAX (1024) bits. Nothing prevents a malicious VF from
providing ptype >= 1024 through VIRTCHNL, resulting in a write past
the end of the bitmap and a kernel page fault.

Reproduced with a custom kernel module injecting a crafted
VIRTCHNL_OP_ADD_RSS_CFG on E810-C QSFP (8086:1592),
FW 4.91 0x800214af 1.3909.0, ICE COMMS DDP 1.3.53.0,
kernel 7.1.0-rc1.

crash_parser: ice_parser_profile_init @ ffffffffc0d61b60
crash_parser: setting ptype=0xffff (max valid=1023)
crash_parser: calling ice_parser_profile_init -- expect OOB crash!
BUG: kernel NULL pointer dereference, address: 0000000000000000
Oops: Oops: 0002 [#1] SMP NOPTI
CPU: 56 UID: 0 PID: 165011 Comm: insmod Kdump: loaded Tainted: G S U OE 7.1.0-rc1 #1
Hardware name: Intel Corporation S2600BPB/S2600BPB
RIP: 0010:ice_parser_profile_init+0x2d/0x1d0 [ice]
Call Trace:
<TASK>
? __pfx_ice_parser_profile_init+0x10/0x10 [ice]
crash_init+0x127/0xff0 [crash_parser]
do_one_initcall+0x45/0x310
do_init_module+0x64/0x270
init_module_from_file+0xcc/0xf0
idempotent_init_module+0x17b/0x280
__x64_sys_finit_module+0x6e/0xe0

Bail out early with -EINVAL when ptype is out of range.

🎖@cveNotify
🚨 CVE-2026-68129
In the Linux kernel, the following vulnerability has been resolved:

gve: fix Rx queue stall on alloc failure

When the system is under extreme memory pressure, page allocations can
fail during the Rx buffer refill loop. If the number of buffers posted
to hardware falls below a critical low threshold and the refill loop
exits due to allocation failures, the queue can stall:

1. The device drops incoming packets because there are no descriptors.
2. Since no packets are processed, no Rx completions are generated.
3. Because no completions occur, NAPI is never scheduled, preventing
the refill loop from running again even after memory is freed.

This results in a permanent queue stall.

Resolve this by introducing a starvation recovery timer for each Rx queue.
If the number of buffers posted to hardware falls below a critical low
threshold, start a timer to periodically reschedule NAPI. Once NAPI runs
and successfully refills the queue above the threshold, the timer is
not rescheduled.

The threshold is set to 32 because a single maximum-sized Receive Segment
Coalescing (RSC) packet can consume up to 19 descriptors in the Rx path.
Lower thresholds (such as 8 or 16) would be insufficient to process a
complete maximum-sized RSC packet, risking packet drops or unexpected
hardware behavior under memory pressure. Setting the threshold to 32
guarantees a safe margin to handle at least one full RSC packet.

🎖@cveNotify
🚨 CVE-2026-68130
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: defer destroy_previous_session() until after NTLM authentication

In ntlm_authenticate(), destroy_previous_session() is called using a
user pointer resolved from the client-supplied NTLM blob username field
before the NTLMv2 response is validated. An authenticated attacker can
set the NTLM blob username to match a victim account and set
PreviousSessionId to the victim's session ID; destroy_previous_session()
destroys the victim's session while ksmbd_decode_ntlmssp_auth_blob()
subsequently rejects the request with -EPERM.

Move destroy_previous_session() and the prev_id assignment to after
ksmbd_decode_ntlmssp_auth_blob() returns success and use sess->user
rather than the pre-authentication lookup result. This matches the
ordering already used by krb5_authenticate(), where
destroy_previous_session() is called only after
ksmbd_krb5_authenticate() returns success.

🎖@cveNotify
🚨 CVE-2026-68131
In the Linux kernel, the following vulnerability has been resolved:

rbd: Reset positive result codes to zero in object map update path

In a reply message to an RBD request, a positive result code indicates
a data payload, which is not allowed for writes. While
rbd_osd_req_callback() already resets a positive result code for writes
to zero, rbd_object_map_callback() does not. This allows a corrupted
reply to an object map update to trigger the rbd_assert(*result < 0) in
__rbd_obj_handle_request(). This happens, because
rbd_object_map_callback() calls rbd_obj_handle_request() ->
__rbd_obj_handle_request() and passes this positive result code. From
__rbd_obj_handle_request(), rbd_obj_advance_write() is called, which
leaves the positive result code unchanged and returns true. Therefore,
the if(done && *result) branch is executed in __rbd_obj_handle_request()
and the assertion triggers.

This patch fixes the issue by adjusting the logic in the
rbd_object_map_callback() path. A positive result code for an object map
update is now reset to zero (similar to rbd_osd_req_callback()), and the
message is subsequently handled the same way as if the result code was
zero from the beginning. Additionally, a WARN_ON_ONCE() is added for
this case.

🎖@cveNotify
🚨 CVE-2026-68132
In the Linux kernel, the following vulnerability has been resolved:

super: fix emergency thaw deadlock on frozen block devices

do_thaw_all_callback() calls bdev_thaw() while holding sb->s_umount
exclusively. If the block device was frozen via bdev_freeze() dropping
the last block layer freeze reference calls fs_bdev_thaw() which
reacquires s_umount:

do_thaw_all_callback(sb)
super_lock_excl(sb) # holds sb->s_umount
bdev_thaw(sb->s_bdev)
mutex_lock(&bdev->bd_fsfreeze_mutex)
# bd_fsfreeze_count drops 1 -> 0
bd_holder_ops->thaw == fs_bdev_thaw
get_bdev_super(bdev)
bdev_super_lock(bdev, true)
super_lock(sb, true)
down_write(&sb->s_umount) # same task: deadlock

The emergency thaw worker deadlocks against itself holding both
s_umount and bd_fsfreeze_mutex. That fscks any subsequent unmount,
freeze, or thaw of that filesystem and block device.

[ 81.878470] sysrq: Show Blocked State
[ 81.880140] task:kworker/0:1 state:D stack:0 pid:11 tgid:11 ppid:2 task_flags:0x4208060 flags:0x00080000
[ 81.884876] Workqueue: events do_thaw_all
[ 81.886656] Call Trace:
[ 81.887759] <TASK>
[ 81.888763] __schedule+0x579/0x1420
[ 81.890372] schedule+0x3a/0x100
[ 81.891794] schedule_preempt_disabled+0x15/0x30
[ 81.893848] rwsem_down_write_slowpath+0x1ea/0x900
[ 81.895191] ? __pfx_do_thaw_all_callback+0x10/0x10
[ 81.896528] down_write+0xbd/0xc0
[ 81.897505] super_lock+0x91/0x180
[ 81.898457] ? __mutex_lock+0xa99/0x1140
[ 81.900748] ? __mutex_unlock_slowpath+0x1f/0x400
[ 81.902069] bdev_super_lock+0x5b/0x150
[ 81.903132] get_bdev_super+0x10/0x60
[ 81.904042] fs_bdev_thaw+0x23/0xf0
[ 81.904755] bdev_thaw+0x82/0x100
[ 81.905484] do_thaw_all_callback+0x2c/0x50
[ 81.906298] __iterate_supers+0x5d/0x130
[ 81.907067] do_thaw_all+0x20/0x40
[ 81.907739] process_one_work+0x206/0x5e0
[ 81.908545] worker_thread+0x1e2/0x3c0
[ 81.909339] ? __pfx_worker_thread+0x10/0x10
[ 81.910171] kthread+0xf4/0x130
[ 81.910799] ? __pfx_kthread+0x10/0x10
[ 81.911528] ret_from_fork+0x2e2/0x3b0
[ 81.912259] ? __pfx_kthread+0x10/0x10
[ 81.913010] ret_from_fork_asm+0x1a/0x30
[ 81.913806] </TASK>

bdev_super_lock() even documents the violated requirement with
lockdep_assert_not_held(&sb->s_umount).

Acquiring bd_fsfreeze_mutex under s_umount also inverts the
bd_fsfreeze_mutex vs. s_umount ordering established by
bdev_{freeze,thaw}() and can thus ABBA against a concurrent block-layer
freeze even when the recursive path isn't hit.

Fix this by not holding s_umount around the bdev_thaw() loop at all. Pin
the superblock with an active reference instead as
filesystems_freeze_callback() does. The active reference keeps the
superblock from being shut down and so ->s_bdev stays valid without
holding s_umount. The block-layer-held freeze is dropped by
fs_bdev_thaw() with FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE exactly as
a regular unfreeze would and thaw_super_locked() handles
filesystem-level freezes as before.

The emergency thaw path has deadlocked like this in one form or
another for a long long time but the current exclusively-held
shape dates back to commit [1] where thaw_bdev() already ended in
thaw_super() with s_umount held by do_thaw_all_callback().

🎖@cveNotify
🚨 CVE-2026-68134
In the Linux kernel, the following vulnerability has been resolved:

ptp: ptp_s390: Add missing facility check

Only register the physical clock when facility 28 is installed
and PTFF QAF returns that PTFF QPT is available.

🎖@cveNotify
🚨 CVE-2026-68135
In the Linux kernel, the following vulnerability has been resolved:

net: hip04: fix RX buffer leak on build_skb failure

When build_skb() fails in hip04_rx_poll(), the driver jumps to the
refill path without releasing the current RX buffer and its DMA mapping.
Installing a replacement buffer then overwrites the slot references and
leaks both resources.

Keep the current slot intact and return budget so NAPI retries the same
buffer. Also free a newly allocated RX fragment when dma_map_single()
fails.

This issue was found by an in-house static analysis tool.

🎖@cveNotify
🚨 CVE-2026-68136
In the Linux kernel, the following vulnerability has been resolved:

net: gro: fix double aggregation of flush-marked skbs

Commit 0ab03f353d36 ("net-gro: Fix GRO flush when receiving a GSO
packet.") added a flush check to skb_gro_receive(), but
skb_gro_receive_list() lacks the same validation.

As a result, packets marked with NAPI_GRO_CB(skb)->flush may still be
re-aggregated.

This allows already-GRO'd packets with existing frag_list to be
re-aggregated into a new GRO session, corrupting the frag_list chain
structure. When skb_segment() attempts to unpack these malformed packets,
it encounters invalid state and triggers a kernel panic.

Scenario (Tethering/Device forwarding):
1. Driver: Generated aggregated packet P1 via LRO with frag_list
2. Dev A: Receives aggregated fraglist packet and flush flag set
3. Dev A: Re-enters GRO, skb_gro_receive_list() is called
4. Missing flush check allows re-aggregation despite flush flag
5. Frag_list chain becomes corrupted (loops or dangling refs)
6. Dev B: TX path calls skb_segment(), crashes on corrupted frag_list

Root cause in skb_segment():
The check at line ~4891:
if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
(skb_headlen(list_skb) == len || sg)) {

When frag_list is corrupted by double aggregation, when list_skb is
a NULL pointer from skb->next, skb_headlen(list_skb) dereference
NULL/corrupted pointers occurs.

Call Trace:
skb_headlen(NULL skb)
skb_segment
tcp_gso_segment
tcp4_gso_segment
inet_gso_segment
skb_mac_gso_segment
__skb_gso_segment
skb_gso_segment
validate_xmit_skb
validate_xmit_skb_list
sch_direct_xmit
qdisc_restart
__qdisc_run
qdisc_run
net_tx_action

Fix: Add NAPI_GRO_CB(skb)->flush validation to the early-return check in
skb_gro_receive_list(), matching the defensive programming pattern of
skb_gro_receive().

🎖@cveNotify
🚨 CVE-2026-68137
In the Linux kernel, the following vulnerability has been resolved:

net/x25: fix use-after-free in x25_kill_by_neigh()

x25_kill_by_neigh() walks the global X.25 socket list looking for sockets
attached to a terminating neighbour. x25_list_lock protects list membership
while the lookup is in progress, but it does not pin a socket's lifetime
after the lock is dropped.

The function currently drops x25_list_lock before calling lock_sock(s). A
concurrent close can run x25_release(), remove the same socket from
x25_list, and drop the last socket reference in that window. The neighbour
teardown path can then lock or inspect a freed struct sock/struct x25_sock.

Take sock_hold(s) while x25_list_lock still proves that the list entry is
live, then drop the temporary reference after the socket has been locked,
rechecked, and released. Recheck x25_sk(s)->neighbour after lock_sock(),
because another path may have disconnected the socket before this path
acquired the socket lock. Restart the list walk after each disconnect
because the list lock was dropped and the previous iterator state may no
longer be valid.

A QEMU/KASAN run against origin/master reproduced a slab-use-after-free in
x25_kill_by_neigh().

🎖@cveNotify
🚨 CVE-2026-68138
In the Linux kernel, the following vulnerability has been resolved:

net/sched: serialize qdisc_rtab_list against concurrent get/put

qdisc_get_rtab() and qdisc_put_rtab() mutate the process-global singly
linked list qdisc_rtab_list and a plain non-atomic 'int refcnt' with no
lock. This was only safe because every caller historically held the RTNL
mutex, which serialized all rate-table lookups, inserts and frees.

That invariant no longer holds. cls_flower sets
TCF_PROTO_OPS_DOIT_UNLOCKED, so tc_new_tfilter() keeps rtnl_held == false
for it and sets TCA_ACT_FLAGS_NO_RTNL. That flag propagates through
tcf_exts_validate_ex() -> tcf_action_init() -> tcf_action_init_1() ->
tcf_police_init(), which calls qdisc_get_rtab()/qdisc_put_rtab() with the
RTNL mutex NOT held. Two RTM_NEWTFILTER requests on different CPUs, each
adding a flower filter with a police action carrying the same rate, then
race on qdisc_rtab_list and on the non-atomic refcnt, leading to a
use-after-free / double-free of the kmalloc-2k struct qdisc_rate_table.
qdisc_rtab_list is a single global (not per-netns), so the corrupted
object is shared system-wide.

BUG: KASAN: slab-use-after-free in qdisc_put_rtab+0x12f/0x160
qdisc_put_rtab+0x12f/0x160
tcf_police_init+0xda9/0x1590
tcf_action_init_1+0x460/0x6b0
tcf_action_init+0x439/0xa40
tcf_exts_validate_ex+0x42d/0x550
fl_change+0xddd/0x7da0
tc_new_tfilter+0xaa7/0x2420
rtnetlink_rcv_msg+0x95e/0xe90
which belongs to the cache kmalloc-2k of size 2048

Protect qdisc_rtab_list and the refcount with a dedicated spinlock. The
(sleeping, GFP_KERNEL) allocation in qdisc_get_rtab() is performed before
taking the lock; if a concurrent inserter added an identical table in the
meantime the freshly allocated one is freed under the lock, so no
duplicate is leaked. qdisc_put_rtab() now decrements the refcount and
unlinks under the same lock.

🎖@cveNotify
🚨 CVE-2026-68139
In the Linux kernel, the following vulnerability has been resolved:

net/mlx5e: Use sender devcom for MPV master-up

After PCIe DPC recovery, mlx5 reloads the affected functions and
replays multiport affiliation events. In the reported failure, the
first relevant device error was:

pcieport 0000:10:01.1: DPC: containment event
pcieport 0000:10:01.1: PCIe Bus Error: severity=Uncorrected (Fatal)
pcieport 0000:10:01.1: [ 5] SDES (First)

mlx5 recovered the PCI functions and resumed 0000:11:00.1. During
that resume, RDMA multiport binding replayed
MLX5_DRIVER_EVENT_AFFILIATION_DONE and mlx5e sent
MPV_DEVCOM_MASTER_UP. The host then panicked with:

BUG: kernel NULL pointer dereference, address: 0000000000000010
RIP: mlx5_devcom_comp_set_ready+0x5/0x40 [mlx5_core]
RDI: 0000000000000000

Call trace included:

mlx5_devcom_comp_set_ready
mlx5e_devcom_event_mpv
mlx5_devcom_send_event
mlx5_ib_bind_slave_port
mlx5r_mp_probe
mlx5_pci_resume

MPV devcom registration publishes mlx5e private data to the component
peer list before mlx5e_devcom_init_mpv() stores the returned component
device in priv->devcom. A concurrent master-up event can therefore
reach a peer whose private data is visible but whose priv->devcom
backpointer is still NULL.

MPV_DEVCOM_MASTER_UP already carries the sender/master mlx5e private
data as event_data. The ready bit is stored on the shared devcom
component, not on an individual peer. Use the sender devcom when
marking the MPV component ready.

This preserves the readiness transition while avoiding a NULL
dereference of the peer devcom pointer during affiliation replay after
PCI error recovery.

🎖@cveNotify