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: stable@kernel.org
Reported-and-Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
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 @@
}
/* 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;