cifs: sanitize username handling

Currently, it's not very clear whether you're allowed to have a NULL
vol->username or ses->user_name. Some places check for it and some don't.

Make it clear that a NULL pointer is OK in these fields, and ensure that
all the callers check for that.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index 5d9b9acc5fce..bce99e6a4950 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -420,15 +420,20 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
         }
 
         /* convert ses->user_name to unicode and uppercase */
-        len = strlen(ses->user_name);
+        len = ses->user_name ? strlen(ses->user_name) : 0;
         user = kmalloc(2 + (len * 2), GFP_KERNEL);
         if (user == NULL) {
                 cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
                 rc = -ENOMEM;
                 return rc;
         }
-        len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
-        UniStrupr(user);
+
+        if (len) {
+                len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
+                UniStrupr(user);
+        } else {
+                memset(user, '\0', 2);
+        }
 
         rc = crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
                                 (char *)user, 2 * len);