USB: cxacru: potential underflow in cxacru_cm_get_array()

The value of "offd" comes off the instance->rcv_buf[] and we used it as
the offset into an array.  The problem is that we check the upper bound
but not for negative values.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c
index b7eb86ad6bf2c2538e1a5d08d358c9b29f432e76..8a7eb77233b4a7b275e042dfeb965be2f45393f8 100644 (file)
--- a/drivers/usb/atm/cxacru.c
+++ b/drivers/usb/atm/cxacru.c
@@ -686,7 +686,8 @@ static int cxacru_cm_get_array(struct cxacru_data *instance, enum cxacru_cm_requ
 {
        int ret, len;
        __le32 *buf;
-       int offb, offd;
+       int offb;
+       unsigned int offd;
        const int stride = CMD_PACKET_SIZE / (4 * 2) - 1;
        int buflen =  ((size - 1) / stride + 1 + size * 2) * 4;