btrfs: fix memory leak on duplicated memory in the qgroup assign ioctl

On 'btrfs_ioctl_qgroup_assign' we first duplicate the argument as
provided by the user, which is kfree'd in the end. But this was not the
case when allocating memory for 'prealloc'. In this case, if it somehow
failed, then the previous code would go directly into calling
'mnt_drop_write_file', without freeing the string duplicated from the
user space.

Fixes: 4addc1ffd67a ("btrfs: qgroup: preallocate memory before adding a relation")
CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a454b5ba209750c89e1b8c743a10e771d78bc8a8..938286bee6a85b5b051109966e99da314d22ea99 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3740,7 +3740,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
                prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
                if (!prealloc) {
                        ret = -ENOMEM;
-                       goto drop_write;
+                       goto out;
                }
        }