[PATCH] blk-cgroup: fix freeing NULL blkg in blkg_create

[PATCH] blk-cgroup: fix freeing NULL blkg in blkg_create

[Christoph Hellwig]

new_blkg can be NULL if the caller didn't pass in a pre-allocated blkg.
Don't try to free it in that case.

Fixes: 27b642b07a4a ("blk-cgroup: simplify blkg freeing from initialization failure paths")
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-cgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 8faeca6022bea0..c46778d1f3c27d 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -383,7 +383,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk,
 err_put_css:
 	css_put(&blkcg->css);
 err_free_blkg:
-	blkg_free(new_blkg);
+	if (new_blkg)
+		blkg_free(new_blkg);
 	return ERR_PTR(ret);
 }
 
-- 
2.39.1

Re: [PATCH] blk-cgroup: fix freeing NULL blkg in blkg_create

[Chaitanya Kulkarni]

On 2/6/23 07:02, Christoph Hellwig wrote:
> new_blkg can be NULL if the caller didn't pass in a pre-allocated blkg.
> Don't try to free it in that case.
> 
> Fixes: 27b642b07a4a ("blk-cgroup: simplify blkg freeing from initialization failure paths")
> Reported-by: Yi Zhang <yi.zhang@redhat.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

This should fix the issue reported by Yi, it will be great
to get tested by though.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck

Re: [PATCH] blk-cgroup: fix freeing NULL blkg in blkg_create

[Jens Axboe]

On Mon, 06 Feb 2023 16:02:01 +0100, Christoph Hellwig wrote:
> new_blkg can be NULL if the caller didn't pass in a pre-allocated blkg.
> Don't try to free it in that case.
> 
> 

Applied, thanks!

[1/1] blk-cgroup: fix freeing NULL blkg in blkg_create
      commit: 28e538a3093833cbac3e28dd511a8b74629d737a

Best regards,
-- 
Jens Axboe