[PATCH 4.4 03/41] cifs: fix incorrect check for null pointer in header_assemble

Greg Kroah-Hartman
2021-10-04T12:54:10Z

From: Steve French <stfrench@microsoft.com>

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>
---
fs/cifs/connect.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2961,9 +2961,10 @@ cifs_match_super(struct super_block *sb,
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;