In the Linux kernel, the following vulnerability has been resolved:
drm/xe/pt: Reset current_op in xe_pt_update_ops_init()
xe_pt_update_ops_init() fails to reset current_op to 0. On the
vm_bind path, ops_execute() calls xe_pt_update_ops_prepare() inside
the xe_validation_guard() / drm_exec_until_all_locked() loop. When
that loop retries due to lock contention or OOM eviction
(drm_exec_retry_on_contention() / xe_validation_retry_on_oom()),
xe_pt_update_ops_prepare() runs again on the same vops, and each
call to bind_op_prepare() increments current_op without resetting it.
After N retries current_op exceeds the array size allocated by
xe_vma_ops_alloc(), causing an out-of-bounds write into
SLUB-poisoned memory and a subsequent UAF crash in
xe_migrate_update_pgtables_cpu() when reading the corrupted pt_op->bind.
Also reset needs_svm_lock and needs_invalidation which are derived in
the same prepare pass and would otherwise cause wrong migrate ops
selection and redundant TLB invalidation on retry.
Fix this by resetting current_op, needs_svm_lock and needs_invalidation
in xe_pt_update_ops_init().
v2 (Matt):
- Add details in commit message.
- Add Fixes tag and Cc to stable@vger.kernel.org
(cherry picked from commit 046045543e530605c441063535e7dca0075369a6)