From: Johan Hovold <johan@kernel.org>
Date: Mon, 6 Mar 2017 16:36:40 +0000 (+0100)
Subject: USB: serial: io_ti: fix information leak in completion handler
X-Git-Tag: v3.12.73~120
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ef598b806384182a74f2aa9bc24a0284faf3940e;p=thirdparty%2Fkernel%2Fstable.git

USB: serial: io_ti: fix information leak in completion handler

commit 654b404f2a222f918af9b0cd18ad469d0c941a8e upstream.

Add missing sanity check to the bulk-in completion handler to avoid an
integer underflow that can be triggered by a malicious device.

This avoids leaking 128 kB of memory content from after the URB transfer
buffer to user space.

Fixes: 8c209e6782ca ("USB: make actual_length in struct urb field u32")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index 2e4589a7b9820..e527a27808554 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -1658,7 +1658,7 @@ static void edge_bulk_in_callback(struct urb *urb)
 
 	port_number = edge_port->port->port_number;
 
-	if (edge_port->lsr_event) {
+	if (urb->actual_length > 0 && edge_port->lsr_event) {
 		edge_port->lsr_event = 0;
 		dev_dbg(dev, "%s ===== Port %u LSR Status = %02x, Data = %02x ======\n",
 			__func__, port_number, edge_port->lsr_mask, *data);