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Date:   Fri, 9 Aug 2019 16:52:06 -0400 (EDT)
From:   Alan Stern <stern@rowland.harvard.edu>
To:     syzbot <syzbot+22ae4e3b9fcc8a5c153a@syzkaller.appspotmail.com>
cc:     andreyknvl@google.com, <gregkh@linuxfoundation.org>,
        <gustavo@embeddedor.com>, <linux-kernel@vger.kernel.org>,
        <linux-usb@vger.kernel.org>, <syzkaller-bugs@googlegroups.com>
Subject: Re: KASAN: use-after-free Read in usb_kill_urb
In-Reply-To: <0000000000007e2e84058fb46c49@google.com>
Message-ID: <Pine.LNX.4.44L0.1908091646230.1630-100000@iolanthe.rowland.org>
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Sender: linux-kernel-owner@vger.kernel.org
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On Fri, 9 Aug 2019, syzbot wrote:

> Hello,
> 
> syzbot has tested the proposed patch and the reproducer did not trigger  
> crash:
> 
> Reported-and-tested-by:  
> syzbot+22ae4e3b9fcc8a5c153a@syzkaller.appspotmail.com
> 
> Tested on:
> 
> commit:         e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> patch:          https://syzkaller.appspot.com/x/patch.diff?x=173f2d2c600000
> 
> Note: testing is done by a robot and is best-effort only.

This shows that this bug is a duplicate of extid=30cf45ebfe0b0c4847a1.  
This fact is also visible in the console logs; both have lines saying 
something like:

[  549.416341][   T22] sysfs: cannot create duplicate filename '/class/usbmisc/ldusb0'

and

[  549.958755][   T22] ldusb 1-1:0.28: Not able to get a minor for this device.

preceding the invalid access.

Alan Stern