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Date:   Sat, 26 Mar 2022 15:43:47 +0300
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Subject: Re: [syzbot] KMSAN: uninit-value in ax88179_led_setting
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To:     David Kahurani <k.kahurani@gmail.com>, davem@davemloft.net,
        jgg@ziepe.ca, kuba@kernel.org, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        phil@philpotter.co.uk, syzkaller-bugs@googlegroups.com,
        syzbot+d3dbdf31fbe9d8f5f311@syzkaller.appspotmail.com,
        arnd@arndb.de
References: <CAAZOf27PHWxdZifZpQYfTHb3h=qk22jRc6-A2LvBkLTR6xNOKg@mail.gmail.com>
 <CAAZOf24Gux0bfS-QGgjcd93NpcpxeA5xU5n2k+EhhyphJo-Mmg@mail.gmail.com>
From:   Pavel Skripkin <paskripkin@gmail.com>
In-Reply-To: <CAAZOf24Gux0bfS-QGgjcd93NpcpxeA5xU5n2k+EhhyphJo-Mmg@mail.gmail.com>
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Hi David,

On 3/26/22 14:47, David Kahurani wrote:
>>
>> Signed-off-by: David Kahurani <k.kahurani@gmail.com>
>> Reported-by: syzbot+d3dbdf31fbe9d8f5f311@syzkaller.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