linux-kernel - [PATCH] media: dvb-usb: dw2102: fix null-ptr-deref in s6x0_i2c

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Message-Id: <20250620213106.3215886-1-alexguo1023@gmail.com>
Date: Fri, 20 Jun 2025 17:31:06 -0400
From: Alex Guo <alexguo1023@...il.com>
To: mchehab@...nel.org
Cc: alexguo1023@...il.com,
	hverkuil@...all.nl,
	linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] media: dvb-usb: dw2102: fix null-ptr-deref in s6x0_i2c_transfer

msg is controlled by user. If accessing msg.buf without sanity
check, null pointer deref would happen. We add check on
msg.len to prevent crash.

Similar commit: commit 0ed554fd769a ("media: dvb-usb: az6027:
fix null-ptr-deref in az6027_i2c_xfer()")

Signed-off-by: Alex Guo <alexguo1023@...il.com>
---
 drivers/media/usb/dvb-usb/dw2102.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/dvb-usb/dw2102.c b/drivers/media/usb/dvb-usb/dw2102.c
index 54493bc490ae..bc30dc6072e6 100644
--- a/drivers/media/usb/dvb-usb/dw2102.c
+++ b/drivers/media/usb/dvb-usb/dw2102.c
@@ -606,6 +606,10 @@ static int s6x0_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
 		case (DW2102_RC_QUERY): {
 			u8 ibuf[5];
 
+			if (msg[j].len < 2) {
+				ret = -EOPNOTSUPP;
+				goto unlock;
+			}
 			dw210x_op_rw(d->udev, 0xb8, 0, 0,
 				     ibuf, 5, DW210X_READ_MSG);
 			memcpy(msg[j].buf, ibuf + 3, 2);
@@ -613,7 +617,11 @@ static int s6x0_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
 		}
 		case (DW2102_VOLTAGE_CTRL): {
 			u8 obuf[2];
-
+			
+			if (msg[j].len < 2) {
+				ret = -EOPNOTSUPP;
+				goto unlock;
+			}
 			obuf[0] = 1;
 			obuf[1] = msg[j].buf[1];/* off-on */
 			dw210x_op_rw(d->udev, 0x8a, 0, 0,
@@ -627,6 +635,10 @@ static int s6x0_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
 		case (DW2102_LED_CTRL): {
 			u8 obuf[2];
 
+			if (msg[j].len < 1) {
+				ret = -EOPNOTSUPP;
+				goto unlock;
+			}
 			obuf[0] = 5;
 			obuf[1] = msg[j].buf[0];
 			dw210x_op_rw(d->udev, 0x8a, 0, 0,
@@ -640,6 +652,10 @@ static int s6x0_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
 		 * case 0xa0: eeprom
 		 */
 		default: {
+			if (msg[j].len < 1) {
+				ret = -EOPNOTSUPP;
+				goto unlock;
+			}
 			if (msg[j].flags == I2C_M_RD) {
 				/* read registers */
 				u8 ibuf[MAX_XFER_SIZE];
-- 
2.34.1