drm/amdgpu: fix integer overflow test in amdgpu_bo_list_create()

We accidentally left out the size of the amdgpu_bo_list struct.  It
could lead to memory corruption on 32 bit systems.  You'd have to
pick the absolute maximum and set "num_entries == 59652323" then size
would wrap to 16 bytes.

Fixes: 920990c ("drm/amdgpu: allocate the bo_list array after the list")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Bas Nieuwenhuizen <basni@chromium.org>
Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c

@@ -67,7 +67,8 @@ int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
 	unsigned i;
 	int r;
 
-	if (num_entries > SIZE_MAX / sizeof(struct amdgpu_bo_list_entry))
+	if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list))
+				/ sizeof(struct amdgpu_bo_list_entry))
 		return -EINVAL;
 
 	size = sizeof(struct amdgpu_bo_list);