Messages in this thread | | | Date | Wed, 17 May 2023 07:10:34 +0200 | From | zzam@gentoo ... | Subject | Re: [PATCH 05/24] media: dvb-usb-v2: ec168: fix null-ptr-deref in ec168_i2c_xfer() |
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Am 13.05.23 um 19:57 schrieb Mauro Carvalho Chehab: > From: Wei Chen <harperchen1110@gmail.com> > > In ec168_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. > If accessing msg[i].buf[0] without sanity check, null pointer 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()") > Review comment below.
> Link: https://lore.kernel.org/linux-media/20230313085853.3252349-1-harperchen1110@gmail.com > Signed-off-by: Wei Chen <harperchen1110@gmail.com> > Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> > --- > drivers/media/usb/dvb-usb-v2/ec168.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/media/usb/dvb-usb-v2/ec168.c b/drivers/media/usb/dvb-usb-v2/ec168.c > index 7ed0ab9e429b..0e4773fc025c 100644 > --- a/drivers/media/usb/dvb-usb-v2/ec168.c > +++ b/drivers/media/usb/dvb-usb-v2/ec168.c > @@ -115,6 +115,10 @@ static int ec168_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > while (i < num) { > if (num > i + 1 && (msg[i+1].flags & I2C_M_RD)) { > if (msg[i].addr == ec168_ec100_config.demod_address) { > + if (msg[i].len < 1) { > + i = -EOPNOTSUPP; > + break; > + } > req.cmd = READ_DEMOD; > req.value = 0; > req.index = 0xff00 + msg[i].buf[0]; /* reg */ > @@ -131,6 +135,10 @@ static int ec168_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > } > } else { > if (msg[i].addr == ec168_ec100_config.demod_address) { > + if (msg[i].len < 1) { > + i = -EOPNOTSUPP; > + break; > + } The check condition should be msg[i].len < 2 or != 2. The following lines access msg[i].buf elements 0 and 1. > req.cmd = WRITE_DEMOD; > req.value = msg[i].buf[1]; /* val */ > req.index = 0xff00 + msg[i].buf[0]; /* reg */ > @@ -139,6 +147,10 @@ static int ec168_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > ret = ec168_ctrl_msg(d, &req); > i += 1; > } else { > + if (msg[i].len < 1) { > + i = -EOPNOTSUPP; > + break; > + } > req.cmd = WRITE_I2C; > req.value = msg[i].buf[0]; /* val */ > req.index = 0x0100 + msg[i].addr; /* I2C addr */
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