From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 18 Nov 2022 14:48:00 +0300
Subject: [PATCH] cifs: Use after free in debug code
Git-commit: f391d6ee002ea022c62dc0b09d0578f3ccce81be
References: git-fixes
Patch-mainline: v6.1-rc6

This debug code dereferences "old_iface" after it was already freed by
the call to release_iface().  Re-order the debugging to avoid this
issue.

Fixes: b54034a73baf ("cifs: during reconnect, update interface if necessary")
Cc: stable@vger.kernel.org # 5.19+
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/sess.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 92e4278ec35d..9e7d9f0baa18 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -302,14 +302,14 @@ cifs_chan_update_iface(struct cifs_ses *ses, struct TCP_Server_Info *server)
 
 	/* now drop the ref to the current iface */
 	if (old_iface && iface) {
-		kref_put(&old_iface->refcount, release_iface);
 		cifs_dbg(FYI, "replacing iface: %pIS with %pIS\n",
 			 &old_iface->sockaddr,
 			 &iface->sockaddr);
+		kref_put(&old_iface->refcount, release_iface);
 	} else if (old_iface) {
-		kref_put(&old_iface->refcount, release_iface);
 		cifs_dbg(FYI, "releasing ref to iface: %pIS\n",
 			 &old_iface->sockaddr);
+		kref_put(&old_iface->refcount, release_iface);
 	} else {
 		WARN_ON(!iface);
 		cifs_dbg(FYI, "adding new iface: %pIS\n", &iface->sockaddr);
-- 
2.38.1