fs/mount_setattr: always cleanup mount_kattr

Make sure that finish_mount_kattr() is called after mount_kattr was
succesfully built in both the success and failure case to prevent
leaking any references we took when we built it.  We returned early if
path lookup failed thereby risking to leak an additional reference we
took when building mount_kattr when an idmapped mount was requested.

Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 9caccd41541a ("fs: introduce MOUNT_ATTR_IDMAP")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index 659a8f39c61afbf1477ddc207f117894684f1ba3..b696543adab848edc175fd511c83e7cd06dfc3fb 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -4263,12 +4263,11 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
                return err;
 
        err = user_path_at(dfd, path, kattr.lookup_flags, &target);
-       if (err)
-               return err;
-
-       err = do_mount_setattr(&target, &kattr);
+       if (!err) {
+               err = do_mount_setattr(&target, &kattr);
+               path_put(&target);
+       }
        finish_mount_kattr(&kattr);
-       path_put(&target);
        return err;
 }