[PATCH AUTOSEL 6.4 06/25] media: az6007: Fix null-ptr-deref in az6007_i2c_xfer()

Sasha Levin
2023-09-09T01:13:26Z

From: Zhang Shurong <zhang_shurong@foxmail.com>

[ Upstream commit 1047f9343011f2cedc73c64829686206a7e9fc3f ]

In az6007_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 az6007_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()")

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-v2/az6007.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/media/usb/dvb-usb-v2/az6007.c b/drivers/media/usb/dvb-usb-v2/az6007.c
index 7524c90f5da61..6cbfe75791c21 100644
--- a/drivers/media/usb/dvb-usb-v2/az6007.c
+++ b/drivers/media/usb/dvb-usb-v2/az6007.c
@@ -788,6 +788,10 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
if (az6007_xfer_debug)
printk(KERN_DEBUG "az6007: I2C W addr=0x%x len=%d\n",
addr, msgs[i].len);
+ if (msgs[i].len < 1) {
+ ret = -EIO;
+ goto err;
+ }
req = AZ6007_I2C_WR;
index = msgs[i].buf[0];
value = addr | (1 << 8);
@@ -802,6 +806,10 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
if (az6007_xfer_debug)
printk(KERN_DEBUG "az6007: I2C R addr=0x%x len=%d\n",
addr, msgs[i].len);
+ if (msgs[i].len < 1) {
+ ret = -EIO;
+ goto err;
+ }
req = AZ6007_I2C_RD;
index = msgs[i].buf[0];
value = addr;
--
2.40.1