[PATCH v4 2/5] drm/xe/svm: Fix a potential bo UAF
Ghimiray, Himal Prasad
himal.prasad.ghimiray at intel.com
Wed Mar 26 09:31:29 UTC 2025
On 26-03-2025 13:35, Thomas Hellström wrote:
> 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 tag ?
>
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> Reviewed-by: Matthew Brost <matthew.brost at intel.com>
> ---
> drivers/gpu/drm/xe/xe_svm.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index 52613dd8573a..c7424c824a14 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -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);
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