fuse: Fix a potential memory leak for kstrdup()

[PATCH] fuse: Fix a potential memory leak for kstrdup()

Posted by williamsukatube@163.com 3 years, 9 months ago

From: William Dean <williamsukatube@gmail.com>

kfree() is missing on an error path to free the memory allocated by
kstrdup():

  sb->s_subtype = kstrdup(parent_sb->s_subtype, GFP_KERNEL);

So it is better to free it via kfree(sb->s_subtype).

Fixes: 1866d779d5d2a ("fuse: Allow fuse_fill_super_common() for submounts")
Reported-by: Hacash Robot <hacashRobot@santino.com>
Signed-off-by: William Dean <williamsukatube@gmail.com>
---
 fs/fuse/inode.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 8c0665c5dff8..2d10afad07f8 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1449,8 +1449,10 @@ static int fuse_fill_super_submount(struct super_block *sb,
 	get_fuse_inode(root)->nlookup--;
 	sb->s_d_op = &fuse_dentry_operations;
 	sb->s_root = d_make_root(root);
-	if (!sb->s_root)
+	if (!sb->s_root) {
+		kfree(sb->s_subtype);
 		return -ENOMEM;
+	}
 
 	return 0;
 }
-- 
2.25.1

Re: [PATCH] fuse: Fix a potential memory leak for kstrdup()

Posted by Miklos Szeredi 3 years, 9 months ago

On Fri, 15 Jul 2022 at 09:54, <williamsukatube@163.com> wrote:
>
> From: William Dean <williamsukatube@gmail.com>
>
> kfree() is missing on an error path to free the memory allocated by
> kstrdup():
>
>   sb->s_subtype = kstrdup(parent_sb->s_subtype, GFP_KERNEL);
>
> So it is better to free it via kfree(sb->s_subtype).

Not needed.  s_subtype will be freed in __put_super().

Thanks,
Miklos