From: Steve French <stfrench@microsoft.com>
Date: Fri, 7 May 2021 20:00:41 -0500
Subject: [PATCH] smb3: do not attempt multichannel to server which does not
 support it
Git-commit: 9c2dc11df50d1c8537075ff6b98472198e24438e
Patch-mainline: v5.13-rc1
References: bsc#1192606

We were ignoring CAP_MULTI_CHANNEL in the server response - if the
server doesn't support multichannel we should not be attempting it.

See MS-SMB2 section 3.2.5.2

Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/sess.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 63d517b9f2ff..a92a1fb7cb52 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -97,6 +97,12 @@ int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses)
 		return 0;
 	}
 
+	if (!(ses->server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
+		cifs_dbg(VFS, "server %s does not support multichannel\n", ses->server->hostname);
+		ses->chan_max = 1;
+		return 0;
+	}
+
 	/*
 	 * Make a copy of the iface list at the time and use that
 	 * instead so as to not hold the iface spinlock for opening
-- 
2.33.1