cifs: Fix oops in session setup code for null user mounts

For null user mounts, do not invoke string length function
during session setup.

Cc: <stable@kernel.org
Reported-and-Tested-by: Chris Clayton <chris2553@googlemail.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index eb767412177d..551d0c2b9736 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -246,16 +246,15 @@ static void ascii_ssetup_strings(char **pbcc_area, struct cifs_ses *ses,
         /* copy user */
         /* BB what about null user mounts - check that we do this BB */
         /* copy user */
-        if (ses->user_name != NULL)
+        if (ses->user_name != NULL) {
                 strncpy(bcc_ptr, ses->user_name, MAX_USERNAME_SIZE);
+                bcc_ptr += strnlen(ses->user_name, MAX_USERNAME_SIZE);
+        }
         /* else null user mount */
-
-        bcc_ptr += strnlen(ses->user_name, MAX_USERNAME_SIZE);
         *bcc_ptr = 0;
         bcc_ptr++; /* account for null termination */
 
         /* copy domain */
-
         if (ses->domainName != NULL) {
                 strncpy(bcc_ptr, ses->domainName, 256);
                 bcc_ptr += strnlen(ses->domainName, 256);