Messages in this thread Patch in this message | | | Date | Wed, 17 May 2023 08:55:14 +0200 | From | zzam@gentoo ... | Subject | Re: [PATCH 07/24] media: dvb-usb-v2: rtl28xxu: fix null-ptr-deref in rtl28xxu_i2c_xfer |
| |
Am 13.05.23 um 19:57 schrieb Mauro Carvalho Chehab: > From: Zhang Shurong <zhang_shurong@foxmail.com> > > In rtl28xxu_i2c_xfer, msg is controlled by user. When msg[i].buf > is null and msg[i].len is zero, former checks on msg[i].buf would be > passed. Malicious data finally reach rtl28xxu_i2c_xfer. If accessing > msg[i].buf[0] without sanity check, null ptr deref would happen. > We add check on msg[i].len to prevent crash. > > Similar commit: > commit 0ed554fd769a > ("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()") > > Link: https://lore.kernel.org/linux-media/tencent_3623572106754AC2F266B316798B0F6CCA05@qq.com > Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com> > Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> > --- > drivers/media/usb/dvb-usb-v2/rtl28xxu.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c > index 795a012d4020..f7884bb56fcc 100644 > --- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c > +++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c > @@ -176,6 +176,10 @@ static int rtl28xxu_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > ret = -EOPNOTSUPP; > goto err_mutex_unlock; > } else if (msg[0].addr == 0x10) {
Is there a need to compare msg[0].addr and msg[1].addr for the combined write+read transfer?
@Mauro: It seems a lot of i2c_xfer functions do only partial checking of address and direction for these combined write+read transfers. Is this a problem?
> + if (msg[0].len < 1 || msg[1].len < 1) { > + ret = -EOPNOTSUPP; > + goto err_mutex_unlock; > + } > /* method 1 - integrated demod */ > if (msg[0].buf[0] == 0x00) { > /* return demod page from driver cache */ > @@ -189,6 +193,10 @@ static int rtl28xxu_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > ret = rtl28xxu_ctrl_msg(d, &req); > } > } else if (msg[0].len < 2) { > + if (msg[0].len < 1) { The code sequence is correct, but looks a bit strange. Maybe this is better: } else if (msg[0].len < 1) { ret = -EOPNOTSUPP; goto err_mutex_unlock; } else if (msg[0].len < 2) {
> + ret = -EOPNOTSUPP; > + goto err_mutex_unlock; > + } > /* method 2 - old I2C */ > req.value = (msg[0].buf[0] << 8) | (msg[0].addr << 1); > req.index = CMD_I2C_RD; > @@ -217,8 +225,16 @@ static int rtl28xxu_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > ret = -EOPNOTSUPP; > goto err_mutex_unlock; > } else if (msg[0].addr == 0x10) { > + if (msg[0].len < 1) { Is a write of a single byte fine? req.size below will be 0.
> + ret = -EOPNOTSUPP; > + goto err_mutex_unlock; > + } > /* method 1 - integrated demod */ > if (msg[0].buf[0] == 0x00) { > + if (msg[0].len < 2) { > + ret = -EOPNOTSUPP; > + goto err_mutex_unlock; > + } > /* save demod page for later demod access */ > dev->page = msg[0].buf[1]; > ret = 0; > @@ -231,6 +247,10 @@ static int rtl28xxu_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > ret = rtl28xxu_ctrl_msg(d, &req); > } > } else if ((msg[0].len < 23) && (!dev->new_i2c_write)) { > + if (msg[0].len < 1) { > + ret = -EOPNOTSUPP; > + goto err_mutex_unlock; > + } > /* method 2 - old I2C */ > req.value = (msg[0].buf[0] << 8) | (msg[0].addr << 1); > req.index = CMD_I2C_WR;
| |