From 7a9d34be181f081d49419d408498767d1052e328 Mon Sep 17 00:00:00 2001 From: Michael Kuron Date: Sun, 26 Sep 2021 21:51:26 +0100 Subject: media: dib0700: fix undefined behavior in tuner shutdown commit f7b77ebe6d2f49c7747b2d619586d1aa33f9ea91 upstream. This fixes a problem where closing the tuner would leave it in a state where it would not tune to any channel when reopened. This problem was discovered as part of https://github.com/hselasky/webcamd/issues/16. Since adap->id is 0 or 1, this bit-shift overflows, which is undefined behavior. The driver still worked in practice as the overflow would in most environments result in 0, which rendered the line a no-op. When running the driver as part of webcamd however, the overflow could lead to 0xff due to optimizations by the compiler, which would, in the end, improperly shut down the tuner. The bug is a regression introduced in the commit referenced below. The present patch causes identical behavior to before that commit for adap->id equal to 0 or 1. The driver does not contain support for dib0700 devices with more adapters, assuming such even exist. Tests have been performed with the Xbox One Digital TV Tuner on amd64. Not all dib0700 devices are expected to be affected by the regression; this code path is only taken by those with incorrect endpoint numbers. Link: https://lore.kernel.org/linux-media/1d2fc36d94ced6f67c7cc21dcc469d5e5bdd8201.1632689033.git.mchehab+huawei@kernel.org Cc: stable@vger.kernel.org Fixes: 7757ddda6f4f ("[media] DiB0700: add function to change I2C-speed") Signed-off-by: Michael Kuron Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Greg Kroah-Hartman --- drivers/media/usb/dvb-usb/dib0700_core.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers/media/usb/dvb-usb') diff --git a/drivers/media/usb/dvb-usb/dib0700_core.c b/drivers/media/usb/dvb-usb/dib0700_core.c index ef62dd6c5ae4..07d5e9457877 100644 --- a/drivers/media/usb/dvb-usb/dib0700_core.c +++ b/drivers/media/usb/dvb-usb/dib0700_core.c @@ -616,8 +616,6 @@ int dib0700_streaming_ctrl(struct dvb_usb_adapter *adap, int onoff) deb_info("the endpoint number (%i) is not correct, use the adapter id instead", adap->fe_adap[0].stream.props.endpoint); if (onoff) st->channel_state |= 1 << (adap->id); - else - st->channel_state |= 1 << ~(adap->id); } else { if (onoff) st->channel_state |= 1 << (adap->fe_adap[0].stream.props.endpoint-2); -- cgit v1.2.3