[PATCH 5.4 10/85] drm/nouveau/mem: guard against NULL pointer access in mem_del

[Greg Kroah-Hartman]

From: Karol Herbst <kherbst@xxxxxxxxxx>

commit d10285a25e29f13353bbf7760be8980048c1ef2f upstream.

other drivers seems to do something similar

Signed-off-by: Karol Herbst <kherbst@xxxxxxxxxx>
Cc: dri-devel <dri-devel@xxxxxxxxxxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20201006220528.13925-2-kherbst@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/nouveau/nouveau_mem.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/gpu/drm/nouveau/nouveau_mem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_mem.c
@@ -176,6 +176,8 @@ void
 nouveau_mem_del(struct ttm_mem_reg *reg)
 {
 	struct nouveau_mem *mem = nouveau_mem(reg);
+	if (!mem)
+		return;
 	nouveau_mem_fini(mem);
 	kfree(reg->mm_node);
 	reg->mm_node = NULL;