Re: [PATCH] drm/xe: Protect devcoredump_free

[Nirmoy Das <nirmoy.das@linux.intel.com>]

Hi Rodrigo,

On 4/3/2024 4:50 PM, 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.
>
> Fixes: e5f661bb56d4 ("drm/xe/devcoredump: Print errno if VM snapshot was not captured")
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: José Roberto de Souza <jose.souza@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_guc_submit.c | 1 +
>   drivers/gpu/drm/xe/xe_vm.c         | 2 +-
>   2 files changed, 2 insertions(+), 1 deletion(-)
>
> 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..ccb2e1c67c2c 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -3514,7 +3514,7 @@ void xe_vm_snapshot_free(struct xe_vm_snapshot *snap)
>   {
>   	unsigned long i;
>   
> -	if (IS_ERR(snap))
> +	if (!snap || IS_ERR(snap))
>   		return;

You can use IS_ERR_OR_NULL() here.


Regards,

Nirmoy

>   
>   	for (i = 0; i < snap->num_snaps; i++) {