Bug 2535175 (CVE-2026-89800)

Summary: CVE-2026-89800 kernel: drm/nouveau/uvmm: clear the dirty flag when unwinding an OP_UNMAP_SPARSE
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
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   
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A flaw was found in the Linux kernel's drm/nouveau/uvmm component. When an OP_UNMAP_SPARSE operation is performed, a dirty flag is set for the affected memory region. If a subsequent operation within the same job fails, this dirty flag is not properly cleared during the error handling process. This oversight can lead to the memory region remaining in a permanently dirty state, causing all future attempts to bind to that range to fail, resulting in a denial of service for the affected system.
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Description OSIDB Bzimport 2026-09-16 11:08:19 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/nouveau/uvmm: clear the dirty flag when unwinding an OP_UNMAP_SPARSE

A successful OP_UNMAP_SPARSE marks its region dirty with
nouveau_uvma_region_dirty() and defers the teardown to
nouveau_uvmm_bind_job_cleanup(); it does not remove the region from
uvmm->region_mt.

If a later op in the job fails, the unwind path never clears reg->dirty
(set in one place, cleared nowhere) and sets op->reg = NULL, so cleanup
skips the teardown. The region is left in the tree with dirty set and its
completion never signalled. Later binds over that range then fail
permanently -- -ENOENT or -EINVAL from the dirty checks, or an unkillable
wait_for_completion() in bind_validate_region() -- for the lifetime of
the uvmm.

Clear reg->dirty when the unwind reverts the sparse unmap, restoring the
region to the state it was found in.
Comment 1 Mauro Matteo Cascella 2026-09-21 13:38:58 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89800.mbox