cifs: check for bytes_remaining going to zero in CIFS_SessSetup
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: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@kernel.org
Reported-and-Acked-by: David Howells <ebac1d06c1688626821bb0e574a037a7a5354e49@redhat.com>
Signed-off-by: Jeff Layton <4376fbf8623cd7b7c0232225289bb91cedc0a27f@redhat.com>
Signed-off-by: Steve French <d47560e3bac353b8d509d093b1d727868ac7ddf3@us.ibm.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas