From: Phong Tran <tranmanphong@gmail.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: tranmanphong@gmail.com, mchehab@kernel.org,
hans.verkuil@cisco.com, keescook@chromium.org,
skhan@linuxfoundation.org,
linux-kernel-mentees@lists.linuxfoundation.org,
linux-media@vger.kernel.org
Subject: Re: [Linux-kernel-mentees] Analyze syzbot report technisat_usb2_rc_query KASAN
Date: Tue, 2 Jul 2019 21:06:13 +0700 [thread overview]
Message-ID: <cf3f9c63-bd2d-1e26-bfa7-1fd220bc0652@gmail.com> (raw)
In-Reply-To: <20190702044510.GA1045@kroah.com>
On 7/2/19 11:45 AM, Greg KH wrote:
> On Tue, Jul 02, 2019 at 07:49:26AM +0700, Phong Tran wrote:
>> Hello,
>>
>> I did a checking for this report of syzbot [1]
>> From the call stack of dump log:
>>
>> There shows that a problem within technisat_usb2_get_ir()
>>
>> BUG: KASAN: slab-out-of-bounds in technisat_usb2_get_ir
>> drivers/media/usb/dvb-usb/technisat-usb2.c:664 [inline]
>> BUG: KASAN: slab-out-of-bounds in technisat_usb2_rc_query+0x5fa/0x660
>> drivers/media/usb/dvb-usb/technisat-usb2.c:679
>> Read of size 1 at addr ffff8880a8791ea8 by task kworker/0:1/12
>>
>> Take a look into while loop in technisat_usb2_get_ir().
>> I recognized that a problem. The loop will not break out with the condition
>> doesn't reach. Then "b++" will go wrong and buffer will be overflow.
>>
>> while (1) {
>> [...]
>> b++;
>> if (*b == 0xff) {
>> ev.pulse = 0;
>> ev.duration = 888888*2;
>> ir_raw_event_store(d->rc_dev, &ev);
>> break;
>> }
>> }
>>
>> I would propose changing the loop condition by checking the address of the
>> buffer. If acceptable, I will send this patch to the mailing-list.
>> eg:
>>
>> - while (1) {
>> + while (b != (buf + 63)) {
>> [...]
>> }
>>
>> Tested with syzbot, result is good [2].
>>
>> [1] https://syzkaller.appspot.com/bug?extid=eaaaf38a95427be88f4b
>> [2] https://groups.google.com/d/msg/syzkaller-bugs/CySBCKuUOOs/0hKq1CdjCwAJ
>
> Great, can you submit a patch for this?
>
Yes, sent a patch
https://lore.kernel.org/lkml/20190702140211.28399-1-tranmanphong@gmail.com/
Phong.
> thanks,
>
> greg k-h
>
prev parent reply other threads:[~2019-07-02 14:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 0:49 Analyze syzbot report technisat_usb2_rc_query KASAN Phong Tran
2019-07-02 4:45 ` [Linux-kernel-mentees] " Greg KH
2019-07-02 14:06 ` Phong Tran [this message]
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