drm/xe/vm: nuke PTs only after unlinking contested VMAs
In xe_vm_close_and_put(), external-BO VMAs are queued on the contested
list for deferred destruction via xe_vma_destroy_unlocked(). However,
xe_vm_pt_destroy() was previously invoked before processing contested
VMAs, destroying vm->pt_root while those VMAs were still linked to their
respective buffer objects (vm_bo->list.gpuva).
If a concurrent thread evicts one of those shared buffer objects,
xe_bo_trigger_rebind() holding only bo->resv walks the BO's VMAs and, in
fault mode, calls xe_vm_invalidate_vma() -> xe_pt_zap_ptes(). Because
vm->pt_root[tile->id] is already NULL, dereferencing pt->level causes a
NULL ptr deref.
Fix this by deferring xe_vm_free_scratch() and xe_vm_pt_destroy() until
after all contested VMAs have been unlinked and destroyed.
User is reporting hitting a NULL ptr deref in xe_pt_zap_ptes(), which
could be explained by this race.
(cherry picked from commit c2863648959489767f08892fd6e90577d2ea0b6a)
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Sun, 18 Oct 2026 18:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-362 CWE-476 |
Sun, 18 Oct 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: drm/xe/vm: nuke PTs only after unlinking contested VMAs In xe_vm_close_and_put(), external-BO VMAs are queued on the contested list for deferred destruction via xe_vma_destroy_unlocked(). However, xe_vm_pt_destroy() was previously invoked before processing contested VMAs, destroying vm->pt_root while those VMAs were still linked to their respective buffer objects (vm_bo->list.gpuva). If a concurrent thread evicts one of those shared buffer objects, xe_bo_trigger_rebind() holding only bo->resv walks the BO's VMAs and, in fault mode, calls xe_vm_invalidate_vma() -> xe_pt_zap_ptes(). Because vm->pt_root[tile->id] is already NULL, dereferencing pt->level causes a NULL ptr deref. Fix this by deferring xe_vm_free_scratch() and xe_vm_pt_destroy() until after all contested VMAs have been unlinked and destroyed. User is reporting hitting a NULL ptr deref in xe_pt_zap_ptes(), which could be explained by this race. (cherry picked from commit c2863648959489767f08892fd6e90577d2ea0b6a) | |
| Title | drm/xe/vm: nuke PTs only after unlinking contested VMAs | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-18T15:17:20.805Z
Reserved: 2026-09-25T10:25:14.354Z
Link: CVE-2026-98510
Vulnrichment
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NVD
Status : Received
Published: 2026-10-18T16:17:02.203
Modified: 2026-10-18T16:17:02.203
Link: CVE-2026-98510
Redhat
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OpenCVE Enrichment
Updated: 2026-10-18T17:45:06Z