Bug 2356670 (CVE-2025-21911)

Summary: CVE-2025-21911 kernel: drm/imagination: avoid deadlock on fence release
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2025-04-01 16:05:16 UTC
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 ***