ovl: fix error handling in ovl_verify_set_fh()

We hit a BUG on kfree of an ERR_PTR()...

Reported-by: syzbot+ff03fe05c717b82502d0@syzkaller.appspotmail.com
Fixes: 8b88a2e64036 ("ovl: verify upper root dir matches lower root dir")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 9c0ca6a7becfbe56e15efd596fbc6540b4bbd859..efd372312ef1000709827eab0291b760ea224ae1 100644 (file)
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -422,8 +422,10 @@ int ovl_verify_set_fh(struct dentry *dentry, const char *name,
 
        fh = ovl_encode_real_fh(real, is_upper);
        err = PTR_ERR(fh);
-       if (IS_ERR(fh))
+       if (IS_ERR(fh)) {
+               fh = NULL;
                goto fail;
+       }
 
        err = ovl_verify_fh(dentry, name, fh);
        if (set && err == -ENODATA)