Patch "Drivers: hv: vmbus: Ignore CHANNELMSG_TL_CONNECT_RESULT(23)" has been added to the 4.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Drivers: hv: vmbus: Ignore CHANNELMSG_TL_CONNECT_RESULT(23)

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drivers-hv-vmbus-ignore-channelmsg_tl_connect_result.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3340dc2f677ada482be46a2908ee137d723d4bad
Author: Dexuan Cui <decui@xxxxxxxxxxxxx>
Date:   Sun Jan 19 15:29:22 2020 -0800

    Drivers: hv: vmbus: Ignore CHANNELMSG_TL_CONNECT_RESULT(23)
    
    [ Upstream commit ddc9d357b991838c2d975e8d7e4e9db26f37a7ff ]
    
    When a Linux hv_sock app tries to connect to a Service GUID on which no
    host app is listening, a recent host (RS3+) sends a
    CHANNELMSG_TL_CONNECT_RESULT (23) message to Linux and this triggers such
    a warning:
    
    unknown msgtype=23
    WARNING: CPU: 2 PID: 0 at drivers/hv/vmbus_drv.c:1031 vmbus_on_msg_dpc
    
    Actually Linux can safely ignore the message because the Linux app's
    connect() will time out in 2 seconds: see VSOCK_DEFAULT_CONNECT_TIMEOUT
    and vsock_stream_connect(). We don't bother to make use of the message
    because: 1) it's only supported on recent hosts; 2) a non-trivial effort
    is required to use the message in Linux, but the benefit is small.
    
    So, let's not see the warning by silently ignoring the message.
    
    Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
    Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 43eaf54736f4e..462f7f363faab 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -1228,6 +1228,8 @@ channel_message_table[CHANNELMSG_COUNT] = {
 	{ CHANNELMSG_19,			0, NULL },
 	{ CHANNELMSG_20,			0, NULL },
 	{ CHANNELMSG_TL_CONNECT_REQUEST,	0, NULL },
+	{ CHANNELMSG_22,			0, NULL },
+	{ CHANNELMSG_TL_CONNECT_RESULT,		0, NULL },
 };
 
 /*
@@ -1239,23 +1241,14 @@ void vmbus_onmessage(void *context)
 {
 	struct hv_message *msg = context;
 	struct vmbus_channel_message_header *hdr;
-	int size;
 
 	hdr = (struct vmbus_channel_message_header *)msg->u.payload;
-	size = msg->header.payload_size;
 
-	if (hdr->msgtype >= CHANNELMSG_COUNT) {
-		pr_err("Received invalid channel message type %d size %d\n",
-			   hdr->msgtype, size);
-		print_hex_dump_bytes("", DUMP_PREFIX_NONE,
-				     (unsigned char *)msg->u.payload, size);
-		return;
-	}
-
-	if (channel_message_table[hdr->msgtype].message_handler)
-		channel_message_table[hdr->msgtype].message_handler(hdr);
-	else
-		pr_err("Unhandled channel message type %d\n", hdr->msgtype);
+	/*
+	 * vmbus_on_msg_dpc() makes sure the hdr->msgtype here can not go
+	 * out of bound and the message_handler pointer can not be NULL.
+	 */
+	channel_message_table[hdr->msgtype].message_handler(hdr);
 }
 
 /*
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 1fd812ed679b4..45b8ccdfb0852 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -890,6 +890,10 @@ void vmbus_on_msg_dpc(unsigned long data)
 	}
 
 	entry = &channel_message_table[hdr->msgtype];
+
+	if (!entry->message_handler)
+		goto msg_handled;
+
 	if (entry->handler_type	== VMHT_BLOCKING) {
 		ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
 		if (ctx == NULL)
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 8d3ca6da33421..63cd81e5610d1 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -422,6 +422,8 @@ enum vmbus_channel_message_type {
 	CHANNELMSG_19				= 19,
 	CHANNELMSG_20				= 20,
 	CHANNELMSG_TL_CONNECT_REQUEST		= 21,
+	CHANNELMSG_22				= 22,
+	CHANNELMSG_TL_CONNECT_RESULT		= 23,
 	CHANNELMSG_COUNT
 };