[PATCH] ovl: fix null pointer dereference on ofs allocation failure.

[PATCH] ovl: fix null pointer dereference on ofs allocation failure.

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The current error exit path when ofs fails to allocate jumps
to clean-up code that calls ovl_free_fs resulting in a null pointer
dereference on the null ovl pointer.  Fix this by simply returning
with the -ENOMEM status in err.

Detected by CoverityScan, CID#1461284 ("Dereference after null check")

Fixes: 4f3bf9de9eac ("ovl: factor out ovl_free_fs() helper")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 fs/overlayfs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 708afec913ac..8258a194695b 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1154,7 +1154,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	err = -ENOMEM;
 	ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
 	if (!ofs)
-		goto out_err;
+		return err;
 
 	ofs->creator_cred = cred = prepare_creds();
 	if (!cred)
-- 
2.14.1

Re: [PATCH] ovl: fix null pointer dereference on ofs allocation failure.

[Miklos Szeredi]

On Thu, Nov 9, 2017 at 6:47 PM, Colin King <colin.king@canonical.com> wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> The current error exit path when ofs fails to allocate jumps
> to clean-up code that calls ovl_free_fs resulting in a null pointer
> dereference on the null ovl pointer.  Fix this by simply returning
> with the -ENOMEM status in err.
>
> Detected by CoverityScan, CID#1461284 ("Dereference after null check")


Thanks, fixed.

Miklos