linux-kernel - [PATCH] i2c: add sanity check for input SMBus data length

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <tencent_9443A8C45A37693763A6D7D3658367896405@qq.com>
Date: Tue, 20 Jan 2026 21:47:02 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+64ca69977b37604cd6d9@...kaller.appspotmail.com
Cc: bentiss@...nel.org,
	jikos@...nel.org,
	linux-i2c@...r.kernel.org,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	michael.zaidman@...il.com,
	syzkaller-bugs@...glegroups.com
Subject: [PATCH] i2c: add sanity check for input SMBus data length

The value passed to block[0] in the user-constructed data is too large,
exceeding the length that data for SMBus messages can accommodate. This
triggered the out-of-bounds access reported by syzbot [1].

Adding relevant data size checks in the smbus ioctl can prevent this
out-of-bounds access.

[1]
BUG: KASAN: stack-out-of-bounds in ft260_smbus_write+0x19b/0x2f0 drivers/hid/hid-ft260.c:486
Read of size 42 at addr ffffc90003427d81 by task syz.2.65/6119
Call Trace:
 ft260_smbus_write+0x19b/0x2f0 drivers/hid/hid-ft260.c:486
 ft260_smbus_xfer+0x22c/0x640 drivers/hid/hid-ft260.c:736

Reported-by: syzbot+64ca69977b37604cd6d9@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=64ca69977b37604cd6d9
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
 drivers/i2c/i2c-dev.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index e9577f920286..6725a49d6921 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -378,6 +378,14 @@ static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 	    (read_write == I2C_SMBUS_WRITE)) {
 		if (copy_from_user(&temp, data, datasize))
 			return -EFAULT;
+
+		if (temp.block[0] > datasize) {
+			dev_dbg(&client->adapter->dev,
+				"user input data size (%u) is too big "
+				"in ioctl I2C_SMBUS.\n",
+				temp.block[0]);
+			return -EINVAL;
+		}
 	}
 	if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 		/* Convert old I2C block commands to the new
-- 
2.43.0