[PATCH AUTOSEL 6.4 04/25] media: af9005: Fix null-ptr-deref in af9005_i2c_xfer

Sasha Levin
2023-09-09T00:38:16Z

From: Zhang Shurong <zhang_shurong@foxmail.com>

[ Upstream commit f4ee84f27625ce1fdf41e8483fa0561a1b837d10 ]

In af9005_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 af9005_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/af9005.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/media/usb/dvb-usb/af9005.c b/drivers/media/usb/dvb-usb/af9005.c
index 0827bf3d4e8c7..13604e6acdb83 100644
--- a/drivers/media/usb/dvb-usb/af9005.c
+++ b/drivers/media/usb/dvb-usb/af9005.c
@@ -422,6 +422,10 @@ static int af9005_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[],
if (ret == 0)
ret = 2;
} else {
+ if (msg[0].len < 2) {
+ ret = -EOPNOTSUPP;
+ goto unlock;
+ }
/* write one or more registers */
reg = msg[0].buf[0];
addr = msg[0].addr;
@@ -431,6 +435,7 @@ static int af9005_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[],
ret = 1;
}

+unlock:
mutex_unlock(&d->i2c_mutex);
return ret;
}
--
2.40.1