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, 12 insertions, 7 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index a66dcb52988c..b952a21e917b 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1997,10 +1997,16 @@ static int match_session(struct cifs_ses *ses, struct smb_vol *vol)
                         return 0;
                 break;
         default:
+                /* NULL username means anonymous session */
+                if (ses->user_name == NULL) {
+                        if (!vol->nullauth)
+                                return 0;
+                        break;
+                }
+
                 /* anything else takes username/password */
-                if (ses->user_name == NULL)
-                        return 0;
-                if (strncmp(ses->user_name, vol->username,
+                if (strncmp(ses->user_name,
+                            vol->username ? vol->username : "",
                             MAX_USERNAME_SIZE))
                         return 0;
                 if (strlen(vol->username) != 0 &&
@@ -3167,10 +3173,9 @@ cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
                 return -EINVAL;
 
         if (volume_info->nullauth) {
-                cFYI(1, "null user");
-                volume_info->username = kzalloc(1, GFP_KERNEL);
-                if (volume_info->username == NULL)
-                        return -ENOMEM;
+                cFYI(1, "Anonymous login");
+                kfree(volume_info->username);
+                volume_info->username = NULL;
         } else if (volume_info->username) {
                 /* BB fixme parse for domain name here */
                 cFYI(1, "Username: %s", volume_info->username);