[PATCH 4.19 79/79] media: technisat-usb2: break out of loop at end of buffer

Greg Kroah-Hartman
2019-09-19T22:15:33Z

From: Sean Young <sean@mess.org>

commit 0c4df39e504bf925ab666132ac3c98d6cbbe380b upstream.

Ensure we do not access the buffer beyond the end if no 0xff byte
is encountered.

Reported-by: syzbot+eaaaf38a95427be88f4b@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/usb/dvb-usb/technisat-usb2.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)

--- a/drivers/media/usb/dvb-usb/technisat-usb2.c
+++ b/drivers/media/usb/dvb-usb/technisat-usb2.c
@@ -607,10 +607,9 @@ static int technisat_usb2_frontend_attac
static int technisat_usb2_get_ir(struct dvb_usb_device *d)
{
struct technisat_usb2_state *state = d->priv;
- u8 *buf = state->buf;
- u8 *b;
- int ret;
struct ir_raw_event ev;
+ u8 *buf = state->buf;
+ int i, ret;

buf[0] = GET_IR_DATA_VENDOR_REQUEST;
buf[1] = 0x08;
@@ -646,26 +645,25 @@ unlock:
return 0; /* no key pressed */

/* decoding */
- b = buf+1;

#if 0
deb_rc("RC: %d ", ret);
- debug_dump(b, ret, deb_rc);
+ debug_dump(buf + 1, ret, deb_rc);
#endif

ev.pulse = 0;
- while (1) {
- ev.pulse = !ev.pulse;
- ev.duration = (*b * FIRMWARE_CLOCK_DIVISOR * FIRMWARE_CLOCK_TICK) / 1000;
- ir_raw_event_store(d->rc_dev, &ev);
-
- b++;
- if (*b == 0xff) {
+ for (i = 1; i < ARRAY_SIZE(state->buf); i++) {
+ if (buf[i] == 0xff) {
ev.pulse = 0;
ev.duration = 888888*2;
ir_raw_event_store(d->rc_dev, &ev);
break;
}
+
+ ev.pulse = !ev.pulse;
+ ev.duration = (buf[i] * FIRMWARE_CLOCK_DIVISOR *
+ FIRMWARE_CLOCK_TICK) / 1000;
+ ir_raw_event_store(d->rc_dev, &ev);
}

ir_raw_event_handle(d->rc_dev);