cifs: populate empty hostnames for extra channels

Currently, the secondary channels of a multichannel session
also get hostname populated based on the info in primary channel.
However, this will end up with a wrong resolution of hostname to
IP address during reconnect.

This change fixes this by not populating hostname info for all
secondary channels.

Fixes: 5112d80c ("cifs: populate server_hostname for extra channels")
Cc: stable@vger.kernel.org
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/connect.c

@@ -97,6 +97,10 @@ static int reconn_set_ipaddr_from_hostname(struct TCP_Server_Info *server)
 	if (!server->hostname)
 		return -EINVAL;
 
+	/* if server hostname isn't populated, there's nothing to do here */
+	if (server->hostname[0] == '\0')
+		return 0;
+
 	len = strlen(server->hostname) + 3;
 
 	unc = kmalloc(len, GFP_KERNEL);

fs/cifs/sess.c

@@ -301,7 +301,10 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 	/* Auth */
 	ctx.domainauto = ses->domainAuto;
 	ctx.domainname = ses->domainName;
-	ctx.server_hostname = ses->server->hostname;
+
+	/* no hostname for extra channels */
+	ctx.server_hostname = "";
+
 	ctx.username = ses->user_name;
 	ctx.password = ses->password;
 	ctx.sectype = ses->sectype;