cifs: Fix invalid check in __cifs_calc_signature()

The following check would never evaluate to true:
  > if (i == 0 && iov[0].iov_len <= 4)

Because 'i' always starts at 1.

This patch fixes it and also move the header checks outside the for loop
- which makes more sense.

Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 6 insertions, 9 deletions

diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index f23ff848b158..ee2a8ec70056 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -48,26 +48,23 @@ int __cifs_calc_signature(struct smb_rqst *rqst,
 
         /* iov[0] is actual data and not the rfc1002 length for SMB2+ */
         if (is_smb2) {
-                rc = crypto_shash_update(shash,
-                                         iov[0].iov_base, iov[0].iov_len);
+                if (iov[0].iov_len <= 4)
+                        return -EIO;
+                i = 0;
         } else {
                 if (n_vec < 2 || iov[0].iov_len != 4)
                         return -EIO;
+                i = 1; /* skip rfc1002 length */
         }
 
-        for (i = 1; i < n_vec; i++) {
+        for (; i < n_vec; i++) {
                 if (iov[i].iov_len == 0)
                         continue;
                 if (iov[i].iov_base == NULL) {
                         cifs_dbg(VFS, "null iovec entry\n");
                         return -EIO;
                 }
-                if (is_smb2) {
-                        if (i == 0 && iov[0].iov_len <= 4)
-                                break; /* nothing to sign or corrupt header */
-                } else
-                        if (i == 1 && iov[1].iov_len <= 4)
-                                break; /* nothing to sign or corrupt header */
+
                 rc = crypto_shash_update(shash,
                                          iov[i].iov_base, iov[i].iov_len);
                 if (rc) {