From: Malcolm Priestley Date: Tue, 26 Sep 2017 17:10:20 -0400 Subject: [1/2] media: dvb-usb-v2: lmedm04: Improve logic checking of warm start Origin: https://git.linuxtv.org/media_tree.git/commit?id=3d932ee27e852e4904647f15b64dedca51187ad7 Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-16538 Warm start has no check as whether a genuine device has connected and proceeds to next execution path. Check device should read 0x47 at offset of 2 on USB descriptor read and it is the amount requested of 6 bytes. Fix for kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access as Reported-by: Andrey Konovalov Signed-off-by: Malcolm Priestley Signed-off-by: Mauro Carvalho Chehab --- drivers/media/usb/dvb-usb-v2/lmedm04.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) --- a/drivers/media/usb/dvb-usb-v2/lmedm04.c +++ b/drivers/media/usb/dvb-usb-v2/lmedm04.c @@ -494,18 +494,23 @@ static int lme2510_pid_filter(struct dvb static int lme2510_return_status(struct dvb_usb_device *d) { - int ret = 0; + int ret; u8 *data; - data = kzalloc(10, GFP_KERNEL); + data = kzalloc(6, GFP_KERNEL); if (!data) return -ENOMEM; - ret |= usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), - 0x06, 0x80, 0x0302, 0x00, data, 0x0006, 200); - info("Firmware Status: %x (%x)", ret , data[2]); + ret = usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), + 0x06, 0x80, 0x0302, 0x00, + data, 0x6, 200); + if (ret != 6) + ret = -EINVAL; + else + ret = data[2]; + + info("Firmware Status: %6ph", data); - ret = (ret < 0) ? -ENODEV : data[2]; kfree(data); return ret; } @@ -1189,6 +1194,7 @@ static int lme2510_get_adapter_count(str static int lme2510_identify_state(struct dvb_usb_device *d, const char **name) { struct lme2510_state *st = d->priv; + int status; usb_reset_configuration(d->udev); @@ -1197,12 +1203,16 @@ static int lme2510_identify_state(struct st->dvb_usb_lme2510_firmware = dvb_usb_lme2510_firmware; - if (lme2510_return_status(d) == 0x44) { + status = lme2510_return_status(d); + if (status == 0x44) { *name = lme_firmware_switch(d, 0); return COLD; } - return 0; + if (status != 0x47) + return -EINVAL; + + return WARM; } static int lme2510_get_stream_config(struct dvb_frontend *fe, u8 *ts_type,