drm/msm: return an error pointer in msm_gem_prime_get_sg_table()

stable inclusion
from stable-v5.10.121
commit d50b26221fbae540a09ab6314b93c91b2e26abb7
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d50b26221fbae540a09ab6314b93c91b2e26abb7

--------------------------------

[ Upstream commit cf575e31 ]

The msm_gem_prime_get_sg_table() needs to return error pointers on
error.  This is called from drm_gem_map_dma_buf() and returning a
NULL will lead to a crash in that function.

Fixes: ac451467 ("drm/msm: fix msm_gem_prime_get_sg_table()")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/485023/
Link: https://lore.kernel.org/r/YnOmtS5tfENywR9m@kiliSigned-off-by: NDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

drivers/gpu/drm/msm/msm_gem_prime.c

@@ -17,7 +17,7 @@ struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj)
 	int npages = obj->size >> PAGE_SHIFT;
 
 	if (WARN_ON(!msm_obj->pages))  /* should have already pinned! */
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	return drm_prime_pages_to_sg(obj->dev, msm_obj->pages, npages);
 }