[PATCH AUTOSEL 6.4 03/25] media: dw2102: Fix null-ptr-deref in dw2102_i2c_transfer()

Sasha Levin
2023-09-09T00:39:44Z

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 8747960e61461..356fc728d59a8 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,
--
2.40.1