[CIFS] fix static checker warning

Dan Carpenter wrote:

The patch 7f420cee8bd6: "[CIFS] Charge at least one credit, if server
says that it supports multicredit" from Jun 23, 2013, leads to the
following Smatch complaint:

fs/cifs/smb2pdu.c:120 smb2_hdr_assemble()
         warn: variable dereferenced before check 'tcon->ses' (see line 115)

CC: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index f9b74da..53275bf 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -111,7 +111,8 @@ smb2_hdr_assemble(struct smb2_hdr *hdr, __le16 smb2_cmd /* command */ ,
        /* BB FIXME when we do write > 64K add +1 for every 64K in req or rsp */
        /* GLOBAL_CAP_LARGE_MTU will only be set if dialect > SMB2.02 */
        /* See sections 2.2.4 and 3.2.4.1.5 of MS-SMB2 */
-       if (tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU)
+       if ((tcon->ses) &&
+           (tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
                hdr->CreditCharge = cpu_to_le16(1);
        /* else CreditCharge MBZ */