ovl: Fix dereferencing possible ERR_PTR()

commit 97f024b9171e74c4443bbe8a8dce31b917f97ac5 upstream.

if ovl_encode_real_fh() fails, no memory was allocated
and the error in the error-valued pointer should be returned.

Fixes: 9b6faee07470 ("ovl: check ERR_PTR() return value from ovl_encode_fh()")
Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
Cc: <stable@vger.kernel.org> # v4.16+
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 54e5d17..6fe3038 100644 (file)
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -230,9 +230,8 @@ static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
        /* Encode an upper or lower file handle */
        fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) :
                                ovl_dentry_upper(dentry), !enc_lower);
-       err = PTR_ERR(fh);
        if (IS_ERR(fh))
-               goto fail;
+               return PTR_ERR(fh);
 
        err = -EOVERFLOW;
        if (fh->len > buflen)