CVE-2026-74490: tipc: avoid use-after-free in poll trace queue dumps

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2026-74490 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.0 with commit b4b9771bcbbd5839b0f77aba55e2f85989ed6779 and fixed in 6.6.151 with commit d7940bb6a8e7ab28f972c2875cb05783216312dc
	Issue introduced in 5.0 with commit b4b9771bcbbd5839b0f77aba55e2f85989ed6779 and fixed in 6.12.103 with commit 5e82beba4bc1f91d0e64c9c43f2b2fa9cd1c2a7d
	Issue introduced in 5.0 with commit b4b9771bcbbd5839b0f77aba55e2f85989ed6779 and fixed in 6.18.44 with commit bed792737b5f1ba773054dbe984502958bdfe6ce
	Issue introduced in 5.0 with commit b4b9771bcbbd5839b0f77aba55e2f85989ed6779 and fixed in 7.1.8 with commit ac2f787980fdf4364cd5651a4c8128e59b8de3aa
	Issue introduced in 5.0 with commit b4b9771bcbbd5839b0f77aba55e2f85989ed6779 and fixed in 7.2-rc6 with commit b4f1719dfea023220e0e6bd892b087d76b2a6a49

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-74490
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/tipc/socket.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/d7940bb6a8e7ab28f972c2875cb05783216312dc
	https://git.kernel.org/stable/c/5e82beba4bc1f91d0e64c9c43f2b2fa9cd1c2a7d
	https://git.kernel.org/stable/c/bed792737b5f1ba773054dbe984502958bdfe6ce
	https://git.kernel.org/stable/c/ac2f787980fdf4364cd5651a4c8128e59b8de3aa
	https://git.kernel.org/stable/c/b4f1719dfea023220e0e6bd892b087d76b2a6a49