commit: fcda7f4578bbf9717444ca6da8a421d21489d078
From: Jeff Layton <[email protected]>
Date: Wed, 27 Apr 2011 13:25:51 -0400
Subject: [PATCH] cifs: check for bytes_remaining going to zero in
 CIFS_SessSetup

It's possible that when we go to decode the string area in the
SESSION_SETUP response, that bytes_remaining will be 0. Decrementing it at
that point will mean that it can go "negative" and wrap. Check for a
bytes_remaining value of 0, and don't try to decode the string area if
that's the case.

Cc: [email protected]
Reported-and-Acked-by: David Howells <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
Signed-off-by: Steve French <[email protected]>
---
 fs/cifs/sess.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 2e2c911..645114a 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -916,7 +916,9 @@ ssetup_ntlmssp_authenticate:
        }
 
        /* BB check if Unicode and decode strings */
-       if (smb_buf->Flags2 & SMBFLG2_UNICODE) {
+       if (bytes_remaining == 0) {
+               /* no string area to decode, do nothing */
+       } else if (smb_buf->Flags2 & SMBFLG2_UNICODE) {
                /* unicode string area must be word-aligned */
                if (((unsigned long) bcc_ptr - (unsigned long) smb_buf) % 2) {
                        ++bcc_ptr;

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