Hello Dan Carpenter.

Thanks for the report.

On 4/13/22 13:11, Dan Carpenter wrote:

Hello Thomas Hellström,

The patch 3bf3710e3718: "drm/ttm: Add a generic TTM memcpy move for page-based iomem" from Jun 2, 2021, leads to the following Smatch static checker warning:

./include/drm/ttm/ttm_bo_driver.h:259 ttm_bo_move_sync_cleanup() error: NULL dereference inside function 'ttm_bo_move_accel_cleanup()'

./include/drm/ttm/ttm_bo_driver.h 256 static inline void ttm_bo_move_sync_cleanup(struct ttm_buffer_object *bo, 257 struct ttm_resource *new_mem) 258 { --> 259 int ret = ttm_bo_move_accel_cleanup(bo, NULL, true, false, new_mem); ^^^^ Passing a NULL for "fence" will crash. The first place where it will crash is in dma_resv_add_fence() where it does:

Indeed, and this has been discussed thoroughly on dri-devel lately. The bug was introduced in a recent patch that made NULL pointers here crash. Not the patch indicated.

Thanks,

Thomas

WARN_ON(dma_fence_is_container(fence));

 260
 261         WARN_ON(ret);
 262 }

regards, dan carpenter