cifs: sanitize username handling

[Dan Carpenter]

Hello Jeff Layton,

The patch 04febabcf55b: "cifs: sanitize username handling" from Jan
17, 2012, leads to the following static checker warning:

fs/cifs/connect.c:2231 match_session()
error: we previously assumed 'vol->username' could be null (see line 2228)

fs/cifs/connect.c
2219 /* NULL username means anonymous session */
2220 if (ses->user_name == NULL) {
2221 if (!vol->nullauth)
2222 return 0;
2223 break;
2224 }
2225
2226 /* anything else takes username/password */
2227 if (strncmp(ses->user_name,
2228 vol->username ? vol->username : "",
^^^^^^^^^^^^^
We added this check for vol->username here.

2229 CIFS_MAX_USERNAME_LEN))
2230 return 0;
2231 if (strlen(vol->username) != 0 &&
^^^^^^^^^^^^^
But this dereference is not checked.

2232 ses->password != NULL &&
2233 strncmp(ses->password,
2234 vol->password ? vol->password : "",
2235 CIFS_MAX_PASSWORD_LEN))
2236 return 0;

regards,
dan carpenter