cifs: protect updating server->dstaddr with a spinlock

BugLink: https://bugs.launchpad.net/bugs/1878232

[ Upstream commit fada37f6 ]

We use a spinlock while we are reading and accessing the destination address for a server.
We need to also use this spinlock to protect when we are modifying this address from
reconn_set_ipaddr().
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/cifs/connect.c

@@ -342,8 +342,10 @@ static int reconn_set_ipaddr(struct TCP_Server_Info *server)
 		return rc;
 	}
 
+	spin_lock(&cifs_tcp_ses_lock);
 	rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
 				  strlen(ipaddr));
+	spin_unlock(&cifs_tcp_ses_lock);
 	kfree(ipaddr);
 
 	return !rc ? -1 : 0;