Patch "media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()" has been added to the 4.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     media-dvb-usb-az6027-fix-null-ptr-deref-in-az6027_i2.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2a4e0248b43194ae507beb2dcda8ecdffd6970e8
Author: Baisong Zhong <zhongbaisong@xxxxxxxxxx>
Date:   Sun Nov 20 06:59:18 2022 +0000

    media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()
    
    [ Upstream commit 0ed554fd769a19ea8464bb83e9ac201002ef74ad ]
    
    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@xxxxxxxxxxxxxx/
    
    Link: https://lore.kernel.org/linux-media/20221120065918.2160782-1-zhongbaisong@xxxxxxxxxx
    Fixes: 76f9a820c867 ("V4L/DVB: AZ6027: Initial import of the driver")
    Reported-by: Wei Chen <harperchen1110@xxxxxxxxx>
    Signed-off-by: Baisong Zhong <zhongbaisong@xxxxxxxxxx>
    Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/media/usb/dvb-usb/az6027.c b/drivers/media/usb/dvb-usb/az6027.c
index 382c8075ef52..f2b5ba1d2809 100644
--- a/drivers/media/usb/dvb-usb/az6027.c
+++ b/drivers/media/usb/dvb-usb/az6027.c
@@ -978,6 +978,10 @@ 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);