From: Dmitry Vyukov <dvyukov@google.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: anon anon <742991625abc@gmail.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Petr Mladek <pmladek@suse.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
syzkaller <syzkaller@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
DRI <dri-devel@lists.freedesktop.org>,
Linux Fbdev development list <linux-fbdev@vger.kernel.org>
Subject: Re: KASAN: slab-out-of-bounds Write in vgacon_scroll
Date: Wed, 29 Jan 2020 15:59:07 +0100 [thread overview]
Message-ID: <CACT4Y+bavHG8esK3jsv0V40+9+mUOFaSdOD1+prpw6L4Wv816g@mail.gmail.com> (raw)
In-Reply-To: <20200129143754.GA15445@jagdpanzerIV.localdomain>
On Wed, Jan 29, 2020 at 3:40 PM Sergey Senozhatsky
<sergey.senozhatsky@gmail.com> wrote:
>
> Cc-ing Dmitry and Tetsuo
>
> Original Message-id: CAA=061EoW8AmjUrBLsJy5nTDz-1jeArLeB+z6HJuyZud0zZXug@mail.gmail.com
>
> On (20/01/29 23:17), Sergey Senozhatsky wrote:
> > > Hmm. There is something strange about it. I use vga console quite
> > > often, and scrolling happens all the time, yet I can't get the same
> > > out-of-bounds report (nor have I ever seen it in the past), even with
> > > the reproducer. Is it supposed to be executed as it is, or are there
> > > any preconditions? Any chance that something that runs prior to that
> > > reproducer somehow impacts the system? Just asking.
> >
> > These questions were addressed to anon anon (742991625abc@gmail.com),
> > not to Bartlomiej.
>
> Could this be GCC_PLUGIN related?
syzkaller repros are meant to be self-contained, but they don't
capture the image and VM setup (or actual hardware). I suspect it may
have something to do with these bugs.
syzbot has reported a bunch of similar bugs in one of our internal kernels:
KASAN: slab-out-of-bounds Read in vgacon_scroll
KASAN: slab-out-of-bounds Read in vgacon_invert_region
KASAN: use-after-free Write in vgacon_scroll
KASAN: use-after-free Read in vgacon_scroll
KASAN: use-after-free Read in vgacon_invert_region
BUG: unable to handle kernel paging request in vgacon_scroll
But none on upstream kernels. That may be some difference in config?
I actually don't know what affects these things. When I tried to get
at least some coverage of that code in syzkaller I just understood
that relations between all these
tty/pty/ptmx/vt/pt/ldisc/vcs/vcsu/fb/con/dri/drm/etc are complex to
say the least...
next prev parent reply other threads:[~2020-01-29 14:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAA=061EoW8AmjUrBLsJy5nTDz-1jeArLeB+z6HJuyZud0zZXug@mail.gmail.com>
2020-01-28 12:49 ` KASAN: slab-out-of-bounds Write in vgacon_scroll Petr Mladek
2020-01-28 14:58 ` Bartlomiej Zolnierkiewicz
2020-01-29 14:15 ` Sergey Senozhatsky
2020-01-29 14:17 ` Sergey Senozhatsky
2020-01-29 14:40 ` Sergey Senozhatsky
2020-01-29 14:59 ` Dmitry Vyukov [this message]
2020-01-29 15:06 ` Dmitry Vyukov
2020-01-29 17:34 ` Tetsuo Handa
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