patch "USB: serial: visor: handle potential invalid device configuration" added to usb-linus

[<gregkh@linuxfoundation.org>]

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

    USB: serial: visor: handle potential invalid device configuration

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 4842ed5bfcb9daf6660537d70503c18d38dbdbb8 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Sun, 29 Apr 2018 17:41:55 +0200
Subject: USB: serial: visor: handle potential invalid device configuration

If we get an invalid device configuration from a palm 3 type device, we
might incorrectly parse things, and we have the potential to crash in
"interesting" ways.

Fix this up by verifying the size of the configuration passed to us by
the device, and only if it is correct, will we handle it.

Note that this also fixes an information leak of slab data.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ johan: add comment about the info leak ]
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/visor.c | 69 +++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/drivers/usb/serial/visor.c b/drivers/usb/serial/visor.c
index f5373ed2cd45..8ddbecc25d89 100644
--- a/drivers/usb/serial/visor.c
+++ b/drivers/usb/serial/visor.c
@@ -335,47 +335,48 @@ static int palm_os_3_probe(struct usb_serial *serial,
 		goto exit;
 	}
 
-	if (retval == sizeof(*connection_info)) {
-			connection_info = (struct visor_connection_info *)
-							transfer_buffer;
-
-		num_ports = le16_to_cpu(connection_info->num_ports);
-		for (i = 0; i < num_ports; ++i) {
-			switch (
-			   connection_info->connections[i].port_function_id) {
-			case VISOR_FUNCTION_GENERIC:
-				string = "Generic";
-				break;
-			case VISOR_FUNCTION_DEBUGGER:
-				string = "Debugger";
-				break;
-			case VISOR_FUNCTION_HOTSYNC:
-				string = "HotSync";
-				break;
-			case VISOR_FUNCTION_CONSOLE:
-				string = "Console";
-				break;
-			case VISOR_FUNCTION_REMOTE_FILE_SYS:
-				string = "Remote File System";
-				break;
-			default:
-				string = "unknown";
-				break;
-			}
-			dev_info(dev, "%s: port %d, is for %s use\n",
-				serial->type->description,
-				connection_info->connections[i].port, string);
-		}
+	if (retval != sizeof(*connection_info)) {
+		dev_err(dev, "Invalid connection information received from device\n");
+		retval = -ENODEV;
+		goto exit;
 	}
-	/*
-	* Handle devices that report invalid stuff here.
-	*/
+
+	connection_info = (struct visor_connection_info *)transfer_buffer;
+
+	num_ports = le16_to_cpu(connection_info->num_ports);
+
+	/* Handle devices that report invalid stuff here. */
 	if (num_ports == 0 || num_ports > 2) {
 		dev_warn(dev, "%s: No valid connect info available\n",
 			serial->type->description);
 		num_ports = 2;
 	}
 
+	for (i = 0; i < num_ports; ++i) {
+		switch (connection_info->connections[i].port_function_id) {
+		case VISOR_FUNCTION_GENERIC:
+			string = "Generic";
+			break;
+		case VISOR_FUNCTION_DEBUGGER:
+			string = "Debugger";
+			break;
+		case VISOR_FUNCTION_HOTSYNC:
+			string = "HotSync";
+			break;
+		case VISOR_FUNCTION_CONSOLE:
+			string = "Console";
+			break;
+		case VISOR_FUNCTION_REMOTE_FILE_SYS:
+			string = "Remote File System";
+			break;
+		default:
+			string = "unknown";
+			break;
+		}
+		dev_info(dev, "%s: port %d, is for %s use\n",
+			serial->type->description,
+			connection_info->connections[i].port, string);
+	}
 	dev_info(dev, "%s: Number of ports: %d\n", serial->type->description,
 		num_ports);
 
-- 
2.17.0