[PATCH AUTOSEL 4.14 10/16] media: mceusb: sanity check for prescaler value

Sasha Levin
2021-02-24T14:17:53Z

From: Sean Young <sean@mess.org>

[ Upstream commit 9dec0f48a75e0dadca498002d25ef4e143e60194 ]

prescaler larger than 8 would mean the carrier is at most 152Hz,
which does not make sense for IR carriers.

Reported-by: syzbot+6d31bf169a8265204b8d@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/rc/mceusb.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/media/rc/mceusb.c b/drivers/media/rc/mceusb.c
index bf7aaff3aa375..bbbbfd697f9c4 100644
--- a/drivers/media/rc/mceusb.c
+++ b/drivers/media/rc/mceusb.c
@@ -630,11 +630,18 @@ static void mceusb_dev_printdata(struct mceusb_dev *ir, u8 *buf, int buf_len,
data[0], data[1]);
break;
case MCE_RSP_EQIRCFS:
+ if (!data[0] && !data[1]) {
+ dev_dbg(dev, "%s: no carrier", inout);
+ break;
+ }
+ // prescaler should make sense
+ if (data[0] > 8)
+ break;
period = DIV_ROUND_CLOSEST((1U << data[0] * 2) *
(data[1] + 1), 10);
if (!period)
break;
- carrier = (1000 * 1000) / period;
+ carrier = USEC_PER_SEC / period;
dev_dbg(dev, "%s carrier of %u Hz (period %uus)",
inout, carrier, period);
break;
--
2.27.0