drm/amd/display: Add NULL check for kzalloc in 'amdgpu_dm_atomic_commit_tail()'

Add a NULL check for the kzalloc call that allocates memory for
dummy_updates in the amdgpu_dm_atomic_commit_tail function. Previously,
if kzalloc failed to allocate memory and returned NULL, the code would
attempt to use the NULL pointer.

The fix is to check if kzalloc returns NULL, and if so, log an error
message and skip the rest of the current loop iteration with the
continue statement.  This prevents the code from attempting to use the
NULL pointer.

Cc: Julia Lawall <[email protected]>
Cc: Aurabindo Pillai <[email protected]>
Cc: Rodrigo Siqueira <[email protected]>
Cc: Alex Hung <[email protected]>
Cc: Alex Deucher <[email protected]>
Reported-by: Julia Lawall <[email protected]>
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]/
Fixes: 135fd1b ("drm/amd/display: Reduce stack size")
Signed-off-by: Srinivasan Shanmugam <[email protected]>
Reviewed-by: Aurabindo Pillai <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: srishanm

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -9187,6 +9187,10 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 		 * To fix this, DC should permit updating only stream properties.
 		 */
 		dummy_updates = kzalloc(sizeof(struct dc_surface_update) * MAX_SURFACES, GFP_ATOMIC);
+		if (!dummy_updates) {
+			DRM_ERROR("Failed to allocate memory for dummy_updates.\n");
+			continue;
+		}
 		for (j = 0; j < status->plane_count; j++)
 			dummy_updates[j].surface = status->plane_states[0];