From: Zhang Shurong zhang_shurong@foxmail.com
[ Upstream commit 5ae544d94abc8ff77b1b9bf8774def3fa5689b5b ]
In dw2102_i2c_transfer, 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 dw2102_i2c_transfer. 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 950e252cb469 ("[media] dw2102: limit messages to buffer size")
Signed-off-by: Zhang Shurong zhang_shurong@foxmail.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/usb/dvb-usb/dw2102.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/drivers/media/usb/dvb-usb/dw2102.c b/drivers/media/usb/dvb-usb/dw2102.c index 970b84c3f0b5a..b3bb1805829ad 100644 --- a/drivers/media/usb/dvb-usb/dw2102.c +++ b/drivers/media/usb/dvb-usb/dw2102.c @@ -128,6 +128,10 @@ static int dw2102_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
switch (num) { case 2: + if (msg[0].len < 1) { + num = -EOPNOTSUPP; + break; + } /* read stv0299 register */ value = msg[0].buf[0];/* register */ for (i = 0; i < msg[1].len; i++) { @@ -139,6 +143,10 @@ static int dw2102_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], case 1: switch (msg[0].addr) { case 0x68: + if (msg[0].len < 2) { + num = -EOPNOTSUPP; + break; + } /* write to stv0299 register */ buf6[0] = 0x2a; buf6[1] = msg[0].buf[0]; @@ -148,6 +156,10 @@ static int dw2102_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], break; case 0x60: if (msg[0].flags == 0) { + if (msg[0].len < 4) { + num = -EOPNOTSUPP; + break; + } /* write to tuner pll */ buf6[0] = 0x2c; buf6[1] = 5; @@ -159,6 +171,10 @@ static int dw2102_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], dw210x_op_rw(d->udev, 0xb2, 0, 0, buf6, 7, DW210X_WRITE_MSG); } else { + if (msg[0].len < 1) { + num = -EOPNOTSUPP; + break; + } /* read from tuner */ dw210x_op_rw(d->udev, 0xb5, 0, 0, buf6, 1, DW210X_READ_MSG); @@ -166,12 +182,20 @@ static int dw2102_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], } break; case (DW2102_RC_QUERY): + if (msg[0].len < 2) { + num = -EOPNOTSUPP; + break; + } dw210x_op_rw(d->udev, 0xb8, 0, 0, buf6, 2, DW210X_READ_MSG); msg[0].buf[0] = buf6[0]; msg[0].buf[1] = buf6[1]; break; case (DW2102_VOLTAGE_CTRL): + if (msg[0].len < 1) { + num = -EOPNOTSUPP; + break; + } buf6[0] = 0x30; buf6[1] = msg[0].buf[0]; dw210x_op_rw(d->udev, 0xb2, 0, 0,