linux-kernel - [PATCH] media: az6007: Add upper bound check to the data of device state

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Message-ID: <tencent_93C4465D499DEEDF6EE60CB667DC46D0D206@qq.com>
Date: Mon, 21 Apr 2025 22:31:56 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+0192952caa411a3be209@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org,
	mchehab@...nel.org,
	syzkaller-bugs@...glegroups.com
Subject: [PATCH] media: az6007: Add upper bound check to the data of device state

syzbot report a corrupted list in az6007_i2c_xfer. [1]

Before accessing the member data of the struct az6007_device_state, only
the lower boundary of data is checked, but the upper boundary is not checked.
When the value of msgs[i].len is damaged or too large, it will cause out
of bounds access to st->data.

[1]
UBSAN: array-index-out-of-bounds in drivers/media/usb/dvb-usb-v2/az6007.c:821:30
index 4096 is out of range for type 'unsigned char [4096]'
CPU: 1 UID: 0 PID: 5832 Comm: syz-executor328 Not tainted 6.15.0-rc2-syzkaller-00493-gac71fabf1567 #0 PREEMPT(full)
Call Trace:
 <TASK>
 az6007_i2c_xfer+0x549/0xc30 drivers/media/usb/dvb-usb-v2/az6007.c:821
 i2c_transfer_buffer_flags+0x10c/0x190 drivers/i2c/i2c-core-base.c:2343
 i2cdev_read+0x111/0x280 drivers/i2c/i2c-dev.c:155
 do_loop_readv_writev fs/read_write.c:833 [inline]
 do_preadv+0x1af/0x270 fs/read_write.c:1130
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94

Reported-by: syzbot+0192952caa411a3be209@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0192952caa411a3be209
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
 drivers/media/usb/dvb-usb-v2/az6007.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/dvb-usb-v2/az6007.c b/drivers/media/usb/dvb-usb-v2/az6007.c
index 65ef045b74ca..6322894eda27 100644
--- a/drivers/media/usb/dvb-usb-v2/az6007.c
+++ b/drivers/media/usb/dvb-usb-v2/az6007.c
@@ -806,7 +806,8 @@ 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) {
+			if (msgs[i].len < 1 ||
+			    msgs[i].len > ARRAY_SIZE(st->data) - 5) {
 				ret = -EIO;
 				goto err;
 			}
-- 
2.43.0