linux-kernel - Re: net/sctp: use-after-free in __sctp

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Message-ID: <CAAeHK+xaBVcZp7PfH-tYWaxs6rCiaNAivZj4xZLcawFShi6C1Q@mail.gmail.com>
Date:   Wed, 2 Nov 2016 23:42:07 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-sctp@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: net/sctp: use-after-free in __sctp_connect

On Wed, Oct 19, 2016 at 6:57 PM, Marcelo Ricardo Leitner
<marcelo.leitner@...il.com> wrote:
> On Wed, Oct 19, 2016 at 02:25:24PM +0200, Andrey Konovalov wrote:
>> Hi,
>>
>> I've got the following error report while running the syzkaller fuzzer:
>>
>> ==================================================================
>> BUG: KASAN: use-after-free in __sctp_connect+0xabe/0xbf0 at addr
>> ffff88006b1dc610
>
> Seems this is the same that Dmitry Vyukov had reported back in Jan 13th.
> So far I couldn't identify the reason.
> "Good" to know it's still there, thanks for reporting it.

Hi Marcelo,

I've attached a reproducer that might help to figure out the reason.

It triggers the UAF for me in ~10 seconds of running as:
$ gcc -lpthread sctp-connect-uaf-poc.c
$ while true; do ./a.out; done

You need to have KASAN enabled.

>

Download attachment "sctp-connect-uaf-poc.c" of type "application/octet-stream" (3735 bytes)