[PATCH] drm/xe: Protect devcoredump access after unbind

[Souza, Jose]

On Wed, 2024-04-03 at 15:50 -0400, Rodrigo Vivi wrote:
> While we don't have the full flow protection when devcoredump
> is accessed after device unbind. Let's at least for now
> protect against null dereference:
> 
> [  422.766508] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> [  423.119584] RIP: 0010:xe_vm_snapshot_free+0x30/0x180 [xe]
> 
> While at it, I also fixed a non-standard code-declaration block
> on the similar function of xe_guc_submit.
> 
> v2: - Use IS_ERR_OR_NULL (Nirmoy)
>     - Expand to other functions
> 

Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

> Cc: José Roberto de Souza <jose.souza at intel.com>
> Cc: Nirmoy Das <nirmoy.das at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_submit.c | 1 +
>  drivers/gpu/drm/xe/xe_vm.c         | 6 +++---
>  2 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
> index f42f1b567067..6e32f9ce4eb5 100644
> --- a/drivers/gpu/drm/xe/xe_guc_submit.c
> +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
> @@ -1961,6 +1961,7 @@ xe_guc_exec_queue_snapshot_print(struct xe_guc_submit_exec_queue_snapshot *snaps
>  void xe_guc_exec_queue_snapshot_free(struct xe_guc_submit_exec_queue_snapshot *snapshot)
>  {
>  	int i;
> +
>  	if (!snapshot)
>  		return;
>  
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index f4bfb2705956..2a431690d245 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -3426,7 +3426,7 @@ struct xe_vm_snapshot *xe_vm_snapshot_capture(struct xe_vm *vm)
>  
>  void xe_vm_snapshot_capture_delayed(struct xe_vm_snapshot *snap)
>  {
> -	if (IS_ERR(snap))
> +	if (IS_ERR_OR_NULL(snap))
>  		return;
>  
>  	for (int i = 0; i < snap->num_snaps; i++) {
> @@ -3483,7 +3483,7 @@ void xe_vm_snapshot_print(struct xe_vm_snapshot *snap, struct drm_printer *p)
>  {
>  	unsigned long i, j;
>  
> -	if (IS_ERR(snap)) {
> +	if (IS_ERR_OR_NULL(snap)) {
>  		drm_printf(p, "[0].error: %li\n", PTR_ERR(snap));
>  		return;
>  	}
> @@ -3514,7 +3514,7 @@ void xe_vm_snapshot_free(struct xe_vm_snapshot *snap)
>  {
>  	unsigned long i;
>  
> -	if (IS_ERR(snap))
> +	if (IS_ERR_OR_NULL(snap))
>  		return;
>  
>  	for (i = 0; i < snap->num_snaps; i++) {