CVE-2026-74446: drm/amdkfd: hold event_mutex while checkpointing CRIU events

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

In the Linux kernel, the following vulnerability has been resolved:

drm/amdkfd: hold event_mutex while checkpointing CRIU events

kfd_criu_checkpoint_events() counts the entries in p->event_idr via
kfd_get_num_events(), allocates an array sized to that count, and then
walks the same IDR to fill it. Neither the count nor the walk holds
p->event_mutex.

The CRIU checkpoint caller holds only p->mutex. Event create and destroy
(kfd_event_create()/kfd_event_destroy()) take p->event_mutex and do not
take p->mutex, so a second thread in the same process can insert or remove
events between the count and the walk. If an event is inserted, the walk
iterates more entries than were counted and writes past the end of the
ev_privs allocation; if an event is removed, the walk dereferences an
entry that is being freed.

Hold p->event_mutex across the count and the walk so both observe a
consistent view of p->event_idr. The lock is released before
copy_to_user(), which only touches the local buffer. The caller already
holds p->mutex and the create/destroy paths never take p->mutex, so the
p->mutex -> p->event_mutex order is not inverted and no deadlock is
introduced.

(cherry picked from commit ff57e223ab105795b05d3ef3f3c35a5a441bcbaa)

The Linux kernel CVE team has assigned CVE-2026-74446 to this issue.


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

	Issue introduced in 5.18 with commit 40e8a766a761f7fdc8530347527b344fddf6f1a8 and fixed in 6.6.151 with commit 2040b7e39027cb83bb8c7b84a4c95c2f6053c32f
	Issue introduced in 5.18 with commit 40e8a766a761f7fdc8530347527b344fddf6f1a8 and fixed in 6.12.103 with commit 9a7f765985f64fd4a7a58f7bc9cd80a1f4230628
	Issue introduced in 5.18 with commit 40e8a766a761f7fdc8530347527b344fddf6f1a8 and fixed in 6.18.44 with commit 6a52f48157fa7fb81e0c146937fd6c8b0c1cfdbd
	Issue introduced in 5.18 with commit 40e8a766a761f7fdc8530347527b344fddf6f1a8 and fixed in 7.1.8 with commit bed80be08c0bee47fa242a4256ac873477c815f8
	Issue introduced in 5.18 with commit 40e8a766a761f7fdc8530347527b344fddf6f1a8 and fixed in 7.2-rc6 with commit ff8bc5a68a9a70bdc38d61a72c7a49c56063f9d2

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-2026-74446
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:
	drivers/gpu/drm/amd/amdkfd/kfd_events.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/2040b7e39027cb83bb8c7b84a4c95c2f6053c32f
	https://git.kernel.org/stable/c/9a7f765985f64fd4a7a58f7bc9cd80a1f4230628
	https://git.kernel.org/stable/c/6a52f48157fa7fb81e0c146937fd6c8b0c1cfdbd
	https://git.kernel.org/stable/c/bed80be08c0bee47fa242a4256ac873477c815f8
	https://git.kernel.org/stable/c/ff8bc5a68a9a70bdc38d61a72c7a49c56063f9d2