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media: mceusb: sanity check for prescaler value

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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>
This commit is contained in:
Sean Young 2021-01-19 14:53:50 +01:00 committed by Mauro Carvalho Chehab
parent a6f42f5ebb
commit 9dec0f48a7
1 changed files with 8 additions and 1 deletions
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9
drivers/media/rc/mceusb.c
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@ -701,11 +701,18 @@ 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;