Bug 2546360 (CVE-2026-98180)

Summary: CVE-2026-98180 kernel: drm/msm: RCU-free the scheduler-containing ring and VM objects
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: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's Direct Rendering Manager (DRM) MSM driver. When ring buffer or virtual memory objects containing a GPU scheduler are freed, synchronization fences exported to user space continue to reference the deallocated scheduler memory. A local unprivileged attacker can exploit this flaw by querying fence timeline information, triggering a use-after-free condition that leads to a kernel crash and Denial of Service (DoS) or potential information disclosure.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-06 09:05:41 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/msm: RCU-free the scheduler-containing ring and VM objects

Both struct msm_ringbuffer and struct msm_gem_vm embed a struct
drm_gpu_scheduler.  msm_ringbuffer_destroy() and the VM free callback
msm_gem_vm_free() call drm_sched_fini() on the embedded scheduler and then
free the containing object with plain kfree().

drm_sched_fence_get_timeline_name() returns fence->sched->name, and the
scheduler fence keeps a .release callback so it is not ops-detached on
signalling.  A finished fence exported to userspace (the submit out-fence, or
a VM_BIND fence, via sync_file / drm_syncobj) keeps pointing at the embedded
scheduler after the ring/VM is freed, so a later get_timeline_name() --
reachable unprivileged through SYNC_IOC_FILE_INFO -- dereferences freed slab
memory (KASAN slab-use-after-free read).

Per the dma-fence lifetime contract the exporter must keep the data backing a
signalled fence alive for an RCU grace period.  Free the scheduler-containing
objects with kfree_rcu() instead of kfree().

Patchwork: https://patchwork.freedesktop.org/patch/750234/
Comment 1 Mauro Matteo Cascella 2026-10-08 12:48:48 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98180.mbox