cifs: fix incorrect check for null pointer in header_assemble

commit 9ed38fd4a15417cac83967360cf20b853bfab9b6 upstream.

Although very unlikely that the tlink pointer would be null in this case,
get_next_mid function can in theory return null (but not an error)
so need to check for null (not for IS_ERR, which can not be returned
here).

Address warning:

        fs/smbfs_client/connect.c:2392 cifs_match_super()
        warn: 'tlink' isn't an ERR_PTR

Pointed out by Dan Carpenter via smatch code analysis tool

CC: stable@vger.kernel.org
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 73be08ea135f63c73ddc4f30974caf60e48b1412..bc49cd04b725a85ff8fcd1465391c8d34f82ee9a 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3079,9 +3079,10 @@ cifs_match_super(struct super_block *sb, void *data)
        spin_lock(&cifs_tcp_ses_lock);
        cifs_sb = CIFS_SB(sb);
        tlink = cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
-       if (IS_ERR(tlink)) {
+       if (tlink == NULL) {
+               /* can not match superblock if tlink were ever null */
                spin_unlock(&cifs_tcp_ses_lock);
-               return rc;
+               return 0;
        }
        tcon = tlink_tcon(tlink);
        ses = tcon->ses;