From 0ed554fd769a19ea8464bb83e9ac201002ef74ad Mon Sep 17 00:00:00 2001

From: Baisong Zhong <zhongbaisong@huawei.com>

Date: Sun, 20 Nov 2022 06:59:18 +0000

Subject: [PATCH] media: dvb-usb: az6027: fix null-ptr-deref in

 az6027_i2c_xfer()

Git-commit: 0ed554fd769a19ea8464bb83e9ac201002ef74ad

Patch-mainline: v6.2-rc1

References: bsc#1209291 CVE-2023-28328

Wei Chen reports a kernel bug as blew:

general protection fault, probably for non-canonical address

Kasan: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]

...

Call Trace:

<TASK>

__i2c_transfer+0x77e/0x1930 drivers/i2c/i2c-core-base.c:2109

i2c_transfer+0x1d5/0x3d0 drivers/i2c/i2c-core-base.c:2170

i2cdev_ioctl_rdwr+0x393/0x660 drivers/i2c/i2c-dev.c:297

i2cdev_ioctl+0x75d/0x9f0 drivers/i2c/i2c-dev.c:458

vfs_ioctl fs/ioctl.c:51 [inline]

__do_sys_ioctl fs/ioctl.c:870 [inline]

__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856

do_syscall_x64 arch/x86/entry/common.c:50 [inline]

do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd

Rip: 0033:0x7fd834a8bded

In az6027_i2c_xfer(), if msg[i].addr is 0x99,

a null-ptr-deref will caused when accessing msg[i].buf.

For msg[i].len is 0 and msg[i].buf is null.

Fix this by checking msg[i].len in az6027_i2c_xfer().

Link: https://lore.kernel.org/lkml/CAO4mrfcPHB5aQJO=mpqV+p8mPLNg-Fok0gw8gZ=zemAfMGTzMg@mail.gmail.com/

Link: https://lore.kernel.org/linux-media/20221120065918.2160782-1-zhongbaisong@huawei.com

Fixes: 76f9a820c867 ("V4L/DVB: AZ6027: Initial import of the driver")

Reported-by: Wei Chen <harperchen1110@gmail.com>

Signed-off-by: Baisong Zhong <zhongbaisong@huawei.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Acked-by: Vasant Karasulli <vkarasulli@suse.de>

---

 drivers/media/usb/dvb-usb/az6027.c | 4 ++++

 1 file changed, 4 insertions(+)

diff --git a/drivers/media/usb/dvb-usb/az6027.c b/drivers/media/usb/dvb-usb/az6027.c

index cf15988dfb51..7d78ee09be5e 100644

--- a/drivers/media/usb/dvb-usb/az6027.c

+++ b/drivers/media/usb/dvb-usb/az6027.c

@@ -975,6 +975,10 @@ static int az6027_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int n

 		if (msg[i].addr == 0x99) {

 			req = 0xBE;

 			index = 0;

+			if (msg[i].len < 1) {

+				i = -EOPNOTSUPP;

+				break;

+			}

 			value = msg[i].buf[0] & 0x00ff;

 			length = 1;

 			az6027_usb_out_op(d, req, value, index, data, length);

--

2.34.1