[PATCH 4.19 12/52] media: mceusb: sanity check for prescaler value
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-03-05 12:37:41
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From: Sean Young <sean@mess.org> commit 9dec0f48a75e0dadca498002d25ef4e143e60194 upstream. 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/media/rc/mceusb.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/media/rc/mceusb.c
+++ b/drivers/media/rc/mceusb.c@@ -685,11 +685,18 @@ static void mceusb_dev_printdata(struct 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;