linux-cve-announce - CVE-2025-21911: drm/imagination: avoid deadlock on fence release

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Message-ID: <2025040130-CVE-2025-21911-8a57@gregkh>
Date: Tue,  1 Apr 2025 16:39:35 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21911: drm/imagination: avoid deadlock on fence release

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

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

drm/imagination: avoid deadlock on fence release

Do scheduler queue fence release processing on a workqueue, rather
than in the release function itself.

Fixes deadlock issues such as the following:

[  607.400437] ============================================
[  607.405755] WARNING: possible recursive locking detected
[  607.415500] --------------------------------------------
[  607.420817] weston:zfq0/24149 is trying to acquire lock:
[  607.426131] ffff000017d041a0 (reservation_ww_class_mutex){+.+.}-{3:3}, at: pvr_gem_object_vunmap+0x40/0xc0 [powervr]
[  607.436728]
               but task is already holding lock:
[  607.442554] ffff000017d105a0 (reservation_ww_class_mutex){+.+.}-{3:3}, at: dma_buf_ioctl+0x250/0x554
[  607.451727]
               other info that might help us debug this:
[  607.458245]  Possible unsafe locking scenario:

[  607.464155]        CPU0
[  607.466601]        ----
[  607.469044]   lock(reservation_ww_class_mutex);
[  607.473584]   lock(reservation_ww_class_mutex);
[  607.478114]
                *** DEADLOCK ***

The Linux kernel CVE team has assigned CVE-2025-21911 to this issue.


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

	Issue introduced in 6.8 with commit eaf01ee5ba28b97f96a3d3eec4c5fbfb37ee4cde and fixed in 6.12.19 with commit d993ae7360923efd6ade43a32043459a121c28c1
	Issue introduced in 6.8 with commit eaf01ee5ba28b97f96a3d3eec4c5fbfb37ee4cde and fixed in 6.13.7 with commit 9bd8b8d34cf4efba18766d64f817c819ed1bbde7
	Issue introduced in 6.8 with commit eaf01ee5ba28b97f96a3d3eec4c5fbfb37ee4cde and fixed in 6.14 with commit df1a1ed5e1bdd9cc13148e0e5549f5ebcf76cf13

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-2025-21911
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/imagination/pvr_queue.c
	drivers/gpu/drm/imagination/pvr_queue.h


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/d993ae7360923efd6ade43a32043459a121c28c1
	https://git.kernel.org/stable/c/9bd8b8d34cf4efba18766d64f817c819ed1bbde7
	https://git.kernel.org/stable/c/df1a1ed5e1bdd9cc13148e0e5549f5ebcf76cf13