Am 13.05.23 um 19:57 schrieb Mauro Carvalho Chehab:
From: Wei Chen <harperchen1110@xxxxxxxxx>
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@xxxxxxxxx
Signed-off-by: Wei Chen <harperchen1110@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
---
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 */
