Re: KASAN: use-after-free Read in adu_disconnect

From: Johan Hovold <johan@kernel.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Johan Hovold <johan@kernel.org>,
	syzbot <syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	dmg@turingmachine.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	USB list <linux-usb@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: KASAN: use-after-free Read in adu_disconnect
Date: Fri, 20 Sep 2019 11:35:57 +0200	[thread overview]
Message-ID: <20190920093557.GO30545@localhost> (raw)
In-Reply-To: <CACT4Y+aLCfq_eJ0w9EnWN-kiTR7qxgtq+8osCqdNw7L4NYCASg@mail.gmail.com>

On Fri, Sep 20, 2019 at 11:28:22AM +0200, Dmitry Vyukov wrote:
> On Fri, Sep 20, 2019 at 11:21 AM Johan Hovold <johan@kernel.org> wrote:
> >
> > On Fri, Sep 20, 2019 at 11:13:14AM +0200, Dmitry Vyukov wrote:
> > > On Fri, Sep 20, 2019 at 11:08 AM Johan Hovold <johan@kernel.org> wrote:
> > > >
> > > > On Fri, Aug 09, 2019 at 01:24:04PM -0700, syzbot wrote:
> > > > > syzbot has found a reproducer for the following crash on:
> > > > >
> > > > > HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> > > > > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=13871a4a600000
> > > > > kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
> > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=0243cb250a51eeefb8cc
> > > > > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > > > > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11c4c8e2600000
> > > > > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11d80d2c600000
> > > > >
> > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > Reported-by: syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com
> > > > >
> > > > > usb 1-1: USB disconnect, device number 4
> > > > > ==================================================================
> > > > > BUG: KASAN: use-after-free in atomic64_read
> > > > > include/asm-generic/atomic-instrumented.h:836 [inline]
> > > > > BUG: KASAN: use-after-free in atomic_long_read
> > > > > include/asm-generic/atomic-long.h:28 [inline]
> > > > > BUG: KASAN: use-after-free in __mutex_unlock_slowpath+0x96/0x670
> > > > > kernel/locking/mutex.c:1211
> > > > > Read of size 8 at addr ffff8881d1d0aa00 by task kworker/0:1/12
> > > >
> > > > Let's resend and retest with commit id from latest report to make sure
> > > > the patch was actually applied during the last run:
> > >
> > > The reply contains:
> > > patch:          https://syzkaller.appspot.com/x/patch.diff?x=1440268d600000
> > > that's what's being parsed and applied during testing.
> >
> > Thanks for confirming, but I can't seem to find that link in the report
> > from syzbot:
> >
> >         https://lkml.kernel.org/r/000000000000b05ce40592f8521a@google.com
> >
> > Is it supposed to be there?
> 
> I meant the previous one:
> https://lore.kernel.org/linux-usb/000000000000d290e00592e5c17d@google.com/
> 
> The one that you pointed to indeed does not have a patch (was tested
> without any patches). But you did not include any in the request, so
> this WAI.

Ok, that was what I thought. I first tried retriggering the test by
responding to the mail with the patch and a new test directive, but when
that test failed, I figured the patch had not been applied and that I
had to include it directly in the mail when retesting.

Apparently misremembered someone from google responding to a patch with
a test directive, but perhaps they also included the patch in that mail.

Johan