[CIFS] properly account for new user= field in SPNEGO upcall string allocation

...it doesn't look like it's being accounted for at the moment. Also
try to reorganize the calculation to make it a little more evident
what each piece means.

This should probably go to the stable series as well...

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifs_spnego.c

@@ -66,8 +66,8 @@ struct key_type cifs_spnego_key_type = {
 	.describe	= user_describe,
 };
 
-#define MAX_VER_STR_LEN   9 /* length of longest version string e.g.
-				strlen(";ver=0xFF") */
+#define MAX_VER_STR_LEN   8 /* length of longest version string e.g.
+				strlen("ver=0xFF") */
 #define MAX_MECH_STR_LEN 13 /* length of longest security mechanism name, eg
 			       in future could have strlen(";sec=ntlmsspi") */
 #define MAX_IPV6_ADDR_LEN 42 /* eg FEDC:BA98:7654:3210:FEDC:BA98:7654:3210/60 */
@@ -81,11 +81,15 @@ cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
 	struct key *spnego_key;
 	const char *hostname = server->hostname;
 
-	/* BB: come up with better scheme for determining length */
-	/* length of fields (with semicolons): ver=0xyz ipv4= ipaddress host=
-	   hostname sec=mechanism uid=0x uid */
-	desc_len = MAX_VER_STR_LEN + 5 + MAX_IPV6_ADDR_LEN + 1 + 6 +
-		  strlen(hostname) + MAX_MECH_STR_LEN + 8 + (sizeof(uid_t) * 2);
+	/* length of fields (with semicolons): ver=0xyz ip4=ipaddress
+	   host=hostname sec=mechanism uid=0xFF user=username */
+	desc_len = MAX_VER_STR_LEN +
+		   6 /* len of "host=" */ + strlen(hostname) +
+		   5 /* len of ";ipv4=" */ + MAX_IPV6_ADDR_LEN +
+		   MAX_MECH_STR_LEN +
+		   7 /* len of ";uid=0x" */ + (sizeof(uid_t) * 2) +
+		   6 /* len of ";user=" */ + strlen(sesInfo->userName) + 1;
+
 	spnego_key = ERR_PTR(-ENOMEM);
 	description = kzalloc(desc_len, GFP_KERNEL);
 	if (description == NULL)