[PATCH 5.2 123/124] media: technisat-usb2: break out of loop at end of buffer

[Greg Kroah-Hartman]

From: Sean Young <s...@mess.org>

commit 0c4df39e504bf925ab666132ac3c98d6cbbe380b upstream.

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

Reported-by: syzbot+eaaaf38a95427be88...@syzkaller.appspotmail.com
Signed-off-by: Sean Young <s...@mess.org>
Reviewed-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+sams...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@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
@@ -608,10 +608,9 @@ 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;
@@ -647,26 +646,25 @@ 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);