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From:   =?utf-8?Q?Bj=C3=B8rn_Mork?= <bjorn@mork.no>
To:     syzbot <syzbot+ce366e2b8296e25d84f5@syzkaller.appspotmail.com>
Cc:     andreyknvl@google.com, davem@davemloft.net,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        netdev@vger.kernel.org, oliver@neukum.org,
        syzkaller-bugs@googlegroups.com
Subject: Re: divide error in cdc_ncm_update_rxtx_max
Organization: m
References: <00000000000018e4250592c043c3@google.com>
Date:   Tue, 17 Sep 2019 17:46:20 +0200
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        "Tue, 17 Sep 2019 07:09:00 -0700")
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syzbot <syzbot+ce366e2b8296e25d84f5@syzkaller.appspotmail.com> writes:

> syzbot has tested the proposed patch but the reproducer still
> triggered crash:
> divide error in usbnet_update_max_qlen
>
> cdc_ncm 5-1:1.0: setting tx_max =3D 16384
> divide error: 0000 [#1] SMP KASAN
> CPU: 1 PID: 1737 Comm: kworker/1:2 Not tainted 5.3.0-rc7+ #0
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 01/01/2011
> Workqueue: usb_hub_wq hub_event
> RIP: 0010:usbnet_update_max_qlen drivers/net/usb/usbnet.c:344 [inline]
> RIP: 0010:usbnet_update_max_qlen+0x231/0x370 drivers/net/usb/usbnet.c:338

Sure, but that's another error already fixed by Oliver..

I guess this fix worked.  But I believe we should see if this is a more
generic issue than just this single driver/bug.  I fear it is...


Bj=C3=B8rn