drm/xe/svm: Fix a potential bo UAF

If drm_gpusvm_migrate_to_devmem() succeeds, if a cpu access happens to the
range the bo may be freed before xe_bo_unlock(), causing a UAF.

Since the reference is transferred, use xe_svm_devmem_release() to
release the reference on drm_gpusvm_migrate_to_devmem() failure,
and hold a local reference to protect the UAF.

Fixes: 2f118c9491 ("drm/xe: Add SVM VRAM migration")
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250326080551.40201-3-thomas.hellstrom@linux.intel.com
This commit is contained in:
Thomas Hellström 2025-03-26 09:05:48 +01:00
parent 6c55404d4f
commit c9db07cab7

View File

@ -702,11 +702,14 @@ static int xe_svm_alloc_vram(struct xe_vm *vm, struct xe_tile *tile,
list_for_each_entry(block, blocks, link)
block->private = vr;
xe_bo_get(bo);
err = drm_gpusvm_migrate_to_devmem(&vm->svm.gpusvm, &range->base,
&bo->devmem_allocation, ctx);
xe_bo_unlock(bo);
if (err)
xe_bo_put(bo); /* Creation ref */
xe_svm_devmem_release(&bo->devmem_allocation);
xe_bo_unlock(bo);
xe_bo_put(bo);
unlock:
mmap_read_unlock(mm);