Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <CAEAjamsAOJC_EqdX8nTddhN4Xis3d_D1L54Ry3sBdC8L84EdVg@mail.gmail.com>
References: <CAEAjamud-6uX8EmOZy7s6ubWNg=0E1YQZSGK2-SnfsomK8VnGw@mail.gmail.com>
 <CAK8P3a2SnRF9198W4W81WwzEX6yCKFjBLTtTo+97Qcym=99Akg@mail.gmail.com> <CAEAjamsAOJC_EqdX8nTddhN4Xis3d_D1L54Ry3sBdC8L84EdVg@mail.gmail.com>
From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Wed, 21 Nov 2018 11:18:41 +0100
Message-ID: <CACT4Y+Yih790PN6UMOLcZdL930TA2Xmnr82DULo0xWbu7SUpww@mail.gmail.com>
Subject: Re: BUG: unable to handle kernel NULL pointer dereference in write_port
To:     Kyungtae Kim <kt0755@gmail.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Byoungyoung Lee <lifeasageek@gmail.com>,
        DaeRyong Jeong <threeearcat@gmail.com>,
        syzkaller@googlegroups.com, LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Nov 21, 2018 at 11:11 AM, Kyungtae Kim <kt0755@gmail.com> wrote:
> Thank you for your reply.
> But I think this kind of crash can occur in real PC as well, and I'm
> just thinking of some way to stop it in the first place (if possible).
> because malicious users can use this, so as to make the whole system
> (kernel) work incorrectly.

If I am not mistaken this program writes to /dev/port. /dev/port is
strictly privileged.

p.s. if you are extending syzkaller to do new things, it can make
sense to send pull requests upstream. Then we can review the changes
and figure out what should be tested, and what does not make sense to
fuzz. E.g. also don't give /dev/mem to syzkaller ;)