CVE-2026-80539: drm/amdgpu: disallow multiple FENCE chunks in one submit

CVE-2026-80539: drm/amdgpu: disallow multiple FENCE chunks in one submit

[Greg Kroah-Hartman]

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

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

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

drm/amdgpu: disallow multiple FENCE chunks in one submit

amdgpu_cs_pass1() dispatches on chunk_id once per chunk without
rejecting repeated ids. p->uf_bo is a single-slot field, so a
submission carrying two AMDGPU_CHUNK_ID_FENCE chunks runs
amdgpu_cs_p1_user_fence() twice, and the second run overwrites
p->uf_bo with a freshly referenced BO without dropping the reference
taken by the first.

amdgpu_cs_parser_fini() only unrefs the final p->uf_bo, so every FENCE
chunk but the last leaks a BO reference. The leaked BO outlives handle
close and process exit.

Reject duplicate FENCE chunks the same way commit fec5f8e8c6bc
("drm/amdgpu: disallow multiple BO_HANDLES chunks in one submit") did
for p->bo_list.

(cherry picked from commit 665b1fc2a1845206408f9a2c6da67101789edb82)

The Linux kernel CVE team has assigned CVE-2026-80539 to this issue.


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

	Issue introduced in 4.2 with commit d38ceaf99ed015f2a0b9af3499791bd3a3daae21 and fixed in 6.6.153 with commit 070229262ede37d17c4ea596650deb6e5eb5d106
	Issue introduced in 4.2 with commit d38ceaf99ed015f2a0b9af3499791bd3a3daae21 and fixed in 6.12.105 with commit 5f46322e0b84af29e10eb951ff45bd6ea40640de
	Issue introduced in 4.2 with commit d38ceaf99ed015f2a0b9af3499791bd3a3daae21 and fixed in 6.18.46 with commit 71aa45f7bfe46fbc6f51e7832573ff49b6005fea
	Issue introduced in 4.2 with commit d38ceaf99ed015f2a0b9af3499791bd3a3daae21 and fixed in 7.1.10 with commit e3ee74d6dbbe409eb99546a7b0a02b2782f9021d
	Issue introduced in 4.2 with commit d38ceaf99ed015f2a0b9af3499791bd3a3daae21 and fixed in 7.2 with commit 931cd1d1baeae68e8eb2c23bc1f3d8934dca6241

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-2026-80539
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/amdgpu/amdgpu_cs.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/070229262ede37d17c4ea596650deb6e5eb5d106
	https://git.kernel.org/stable/c/5f46322e0b84af29e10eb951ff45bd6ea40640de
	https://git.kernel.org/stable/c/71aa45f7bfe46fbc6f51e7832573ff49b6005fea
	https://git.kernel.org/stable/c/e3ee74d6dbbe409eb99546a7b0a02b2782f9021d
	https://git.kernel.org/stable/c/931cd1d1baeae68e8eb2c23bc1f3d8934dca6241