linux-kernel - [PATCH 2/8] cxacru: check data length is not negative

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Message-ID: <4B080222.50403@simon.arlott.org.uk>
Date:	Sat, 21 Nov 2009 15:07:14 +0000
From:	Simon Arlott <simon@...e.lp0.eu>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [PATCH 2/8] cxacru: check data length is not negative

When attempting to read data that is not actually
an array of values, the length may be negative
which causes an Oops due to a likely access off
the end of the data array.

This bug should not occur under normal use unless
the device returns an invalid response.

Signed-off-by: Simon Arlott <simon@...e.lp0.eu>
---
 drivers/usb/atm/cxacru.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c
index 4a26a6c..8da4a06 100644
--- a/drivers/usb/atm/cxacru.c
+++ b/drivers/usb/atm/cxacru.c
@@ -596,7 +596,7 @@ static int cxacru_cm_get_array(struct cxacru_data *instance, enum cxacru_cm_requ
 	len = ret / 4;
 	for (offb = 0; offb < len; ) {
 		int l = le32_to_cpu(buf[offb++]);
-		if (l > stride || l > (len - offb) / 2) {
+		if (l < 0 || l > stride || l > (len - offb) / 2) {
 			if (printk_ratelimit())
 				usb_err(instance->usbatm, "invalid data length from cm %#x: %d\n",
 					cm, l);
-- 
1.6.3.3

-- 
Simon Arlott

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