lkml.org 
[lkml]   [2019]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Fix an OOB access bug in technisat_usb2_get_ir
On Tue, Aug 20, 2019 at 02:19:16PM -0400, Hui Peng wrote:
> In the while loop of technisat_usb2_get_ir, it scans through
> a fix-sized buffer read from the device side, the termination
> condition of the loop is `*b == 0xff`. If no `0xff` byte is read
> from the device side, OOB access happens.
>
> This patch fixes the bug by adding an upper bound in the while loop.

This issue was fixed in:

https://git.linuxtv.org/media_tree.git/commit/drivers/media/usb/dvb-usb/technisat-usb2.c?id=0c4df39e504bf925ab666132ac3c98d6cbbe380b

Note this limits the loop to the size of the buffer; using the ret
return value might be better.


Sean


>
> Reported-by: Hui Peng <benquike@gmail.com>
> Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
> Signed-off-by: Hui Peng <benquike@gmail.com>
> ---
> drivers/media/usb/dvb-usb/technisat-usb2.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/media/usb/dvb-usb/technisat-usb2.c b/drivers/media/usb/dvb-usb/technisat-usb2.c
> index c659e18b358b..181f5f97af45 100644
> --- a/drivers/media/usb/dvb-usb/technisat-usb2.c
> +++ b/drivers/media/usb/dvb-usb/technisat-usb2.c
> @@ -612,6 +612,7 @@ static int technisat_usb2_get_ir(struct dvb_usb_device *d)
> u8 *b;
> int ret;
> struct ir_raw_event ev;
> + int i = 0;
>
> buf[0] = GET_IR_DATA_VENDOR_REQUEST;
> buf[1] = 0x08;
> @@ -656,11 +657,15 @@ static int technisat_usb2_get_ir(struct dvb_usb_device *d)
>
> ev.pulse = 0;
> while (1) {
> + // only `ret` bytes are read from the device side
> + if (i >= ret)
> + break;
> ev.pulse = !ev.pulse;
> ev.duration = (*b * FIRMWARE_CLOCK_DIVISOR * FIRMWARE_CLOCK_TICK) / 1000;
> ir_raw_event_store(d->rc_dev, &ev);
>
> b++;
> + i++;
> if (*b == 0xff) {
> ev.pulse = 0;
> ev.duration = 888888*2;
> --
> 2.23.0

\
 
 \ /
  Last update: 2019-08-21 12:44    [W:0.040 / U:5.520 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site