On Wed, Jun 25, 2025 at 10:21:58AM -0500, Dan Carpenter wrote:
> There was an error pointer vs NULL bug in __igt_breadcrumbs_smoketest().
> The __mock_request_alloc() function implements the
> smoketest->request_alloc() function pointer. It was supposed to return
> error pointers, but it propogates the NULL return from mock_request()
> so in the event of a failure, it would lead to a NULL pointer
> dereference.
>
> To fix this, change the mock_request() function to return error pointers
> and update all the callers to expect that.
>
> Fixes: 52c0fdb25c7c ("drm/i915: Replace global breadcrumbs with per-context interrupt tracking")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> V2: In v1 I just updated __mock_request_alloc() to return an error pointer
> but in v2, I changed mock_request() to update an error pointer and
> updated all the callers. It's a more extensive change, but hopefully
> cleaner.
Thank you
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>
> drivers/gpu/drm/i915/selftests/i915_request.c | 20 +++++++++----------
> drivers/gpu/drm/i915/selftests/mock_request.c | 2 +-
> 2 files changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
> index 88870844b5bd..2fb7a9e7efec 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_request.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_request.c
> @@ -73,8 +73,8 @@ static int igt_add_request(void *arg)
> /* Basic preliminary test to create a request and let it loose! */
>
> request = mock_request(rcs0(i915)->kernel_context, HZ / 10);
> - if (!request)
> - return -ENOMEM;
> + if (IS_ERR(request))
> + return PTR_ERR(request);
>
> i915_request_add(request);
>
> @@ -91,8 +91,8 @@ static int igt_wait_request(void *arg)
> /* Submit a request, then wait upon it */
>
> request = mock_request(rcs0(i915)->kernel_context, T);
> - if (!request)
> - return -ENOMEM;
> + if (IS_ERR(request))
> + return PTR_ERR(request);
>
> i915_request_get(request);
>
> @@ -160,8 +160,8 @@ static int igt_fence_wait(void *arg)
> /* Submit a request, treat it as a fence and wait upon it */
>
> request = mock_request(rcs0(i915)->kernel_context, T);
> - if (!request)
> - return -ENOMEM;
> + if (IS_ERR(request))
> + return PTR_ERR(request);
>
> if (dma_fence_wait_timeout(&request->fence, false, T) != -ETIME) {
> pr_err("fence wait success before submit (expected timeout)!\n");
> @@ -219,8 +219,8 @@ static int igt_request_rewind(void *arg)
> GEM_BUG_ON(IS_ERR(ce));
> request = mock_request(ce, 2 * HZ);
> intel_context_put(ce);
> - if (!request) {
> - err = -ENOMEM;
> + if (IS_ERR(request)) {
> + err = PTR_ERR(request);
> goto err_context_0;
> }
>
> @@ -237,8 +237,8 @@ static int igt_request_rewind(void *arg)
> GEM_BUG_ON(IS_ERR(ce));
> vip = mock_request(ce, 0);
> intel_context_put(ce);
> - if (!vip) {
> - err = -ENOMEM;
> + if (IS_ERR(vip)) {
> + err = PTR_ERR(vip);
> goto err_context_1;
> }
>
> diff --git a/drivers/gpu/drm/i915/selftests/mock_request.c b/drivers/gpu/drm/i915/selftests/mock_request.c
> index 09f747228dff..1b0cf073e964 100644
> --- a/drivers/gpu/drm/i915/selftests/mock_request.c
> +++ b/drivers/gpu/drm/i915/selftests/mock_request.c
> @@ -35,7 +35,7 @@ mock_request(struct intel_context *ce, unsigned long delay)
> /* NB the i915->requests slab cache is enlarged to fit mock_request */
> request = intel_context_create_request(ce);
> if (IS_ERR(request))
> - return NULL;
> + return request;
>
> request->mock.delay = delay;
> return request;
> --
> 2.47.2
>
