linux-kernel - Re: [syzbot] KMSAN: uninit-value in ax88179_led

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Date:   Sat, 26 Mar 2022 15:43:47 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     David Kahurani <k.kahurani@...il.com>, davem@...emloft.net,
        jgg@...pe.ca, kuba@...nel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, netdev@...r.kernel.org,
        phil@...lpotter.co.uk, syzkaller-bugs@...glegroups.com,
        syzbot+d3dbdf31fbe9d8f5f311@...kaller.appspotmail.com,
        arnd@...db.de
Subject: Re: [syzbot] KMSAN: uninit-value in ax88179_led_setting

Hi David,

On 3/26/22 14:47, David Kahurani wrote:
>>
>> Signed-off-by: David Kahurani <k.kahurani@...il.com>
>> Reported-by: syzbot+d3dbdf31fbe9d8f5f311@...kaller.appspotmail.com
>> ---
>>  drivers/net/usb/ax88179_178a.c | 181 +++++++++++++++++++++++++++------
>>  1 file changed, 152 insertions(+), 29 deletions(-)
>>
>> diff --git a/drivers/net/usb/ax88179_178a.c b/drivers/net/usb/ax88179_178a.c
>> index a31098981..932e21a65 100644
>> --- a/drivers/net/usb/ax88179_178a.c
>> +++ b/drivers/net/usb/ax88179_178a.c
>> @@ -224,9 +224,12 @@ static int __ax88179_write_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
>>   ret = fn(dev, cmd, USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
>>   value, index, data, size);
>>

You've changed __ax88179_write_cmd(), but not __ax88179_read_cmd(). I've 
missed it. Changing  __ax88179_write_cmd() does not help with uninit 
value bugs

Also I believe, __ax88179_read_cmd() should have __must_check annotation 
too, since problem came from it in the first place (I mean after added 
sane error handling inside it)

Next thing is ax88179_read_cmd_nopm() still prone to uninit value bugs, 
since it touches uninitialized `buf` in case of __ax88179_read_cmd() 
error...



I remembered why I gave up on fixing this driver... I hope, you have 
more free time and motivation :)




With regards,
Pavel Skripkin