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Date:   Mon, 19 Apr 2021 14:50:55 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Hao Sun <sunhao.th@gmail.com>
Cc:     dledford@redhat.com, linux-rdma@vger.kernel.org, leon@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: KASAN: use-after-free Read in cma_cancel_operation, rdma_listen
Message-ID: <20210419175055.GA2047089@ziepe.ca>
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On Tue, Apr 13, 2021 at 10:19:25PM +0800, Hao Sun wrote:
> Jason Gunthorpe <jgg@ziepe.ca> 于2021年4月13日周二 下午9:45写道：
> >
> > On Tue, Apr 13, 2021 at 09:42:43PM +0800, Hao Sun wrote:
> > > Jason Gunthorpe <jgg@ziepe.ca> 于2021年4月13日周二 下午9:34写道：
> > > >
> > > > On Tue, Apr 13, 2021 at 11:36:41AM +0800, Hao Sun wrote:
> > > > > Hi
> > > > >
> > > > > When using Healer(https://github.com/SunHao-0/healer/tree/dev) to fuzz
> > > > > the Linux kernel, I found two use-after-free bugs which have been
> > > > > reported a long time ago by Syzbot.
> > > > > Although the corresponding patches have been merged into upstream,
> > > > > these two bugs can still be triggered easily.
> > > > > The original information about Syzbot report can be found here:
> > > > > https://syzkaller.appspot.com/bug?id=8dc0bcd9dd6ec915ba10b3354740eb420884acaa
> > > > > https://syzkaller.appspot.com/bug?id=95f89b8fb9fdc42e28ad586e657fea074e4e719b
> > > >
> > > > Then why hasn't syzbot seen this in a year's time? Seems strange
> > > >
> > >
> > > Seems strange to me too, but the fact is that the reproduction program
> > > in attachment can trigger these two bugs quickly.
> >
> > Do you have this in the C format?
> >
> 
> Just tried to use syz-prog2c to convert the repro-prog to C format.
> The repro program of  rdma_listen was successfully reproduced
> (uploaded in attachment), the other one failed. it looks like
> syz-prog2c may not be able to do the equivalent conversion.
> You can use syz-execprog to execute the reprogram directly, this
> method can reproduce both crashes, I have tried it.

I tried this program and it reliably deadlocks my kernel :|

So there is certainly something here

Jason