Kernel-hardening archive on lore.kernel.org
 help / color / Atom feed
From: Dmitry Vyukov <dvyukov@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	 Elena Petrova <lenaptr@google.com>,
	Alexander Potapenko <glider@google.com>,
	 Linus Torvalds <torvalds@linux-foundation.org>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	 "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	 kasan-dev <kasan-dev@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	 kernel-hardening@lists.openwall.com,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: [PATCH v2 0/3] ubsan: Split out bounds checker
Date: Thu, 28 Nov 2019 14:10:04 +0100
Message-ID: <CACT4Y+b7YtWw57C-1mv1z5bTSa9YpnwhKsgMAtpMuc6J8KXBUg@mail.gmail.com> (raw)
In-Reply-To: <201911270952.D66CD15AEC@keescook>

On Wed, Nov 27, 2019 at 6:59 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Nov 27, 2019 at 10:34:24AM +0100, Dmitry Vyukov wrote:
> > On Wed, Nov 27, 2019 at 7:54 AM Dmitry Vyukov <dvyukov@google.com> wrote:
> > >
> > > On Wed, Nov 27, 2019 at 6:42 AM Kees Cook <keescook@chromium.org> wrote:
> > > >
> > > > On Fri, Nov 22, 2019 at 10:07:29AM +0100, Dmitry Vyukov wrote:
> > > > > On Thu, Nov 21, 2019 at 7:15 PM Kees Cook <keescook@chromium.org> wrote:
> > > > > >
> > > > > > v2:
> > > > > >     - clarify Kconfig help text (aryabinin)
> > > > > >     - add reviewed-by
> > > > > >     - aim series at akpm, which seems to be where ubsan goes through?
> > > > > > v1: https://lore.kernel.org/lkml/20191120010636.27368-1-keescook@chromium.org
> > > > > >
> > > > > > This splits out the bounds checker so it can be individually used. This
> > > > > > is expected to be enabled in Android and hopefully for syzbot. Includes
> > > > > > LKDTM tests for behavioral corner-cases (beyond just the bounds checker).
> > > > > >
> > > > > > -Kees
> > > > >
> > > > > +syzkaller mailing list
> > > > >
> > > > > This is great!
> > > >
> > > > BTW, can I consider this your Acked-by for these patches? :)
> > > >
> > > > > I wanted to enable UBSAN on syzbot for a long time. And it's
> > > > > _probably_ not lots of work. But it was stuck on somebody actually
> > > > > dedicating some time specifically for it.
> > > >
> > > > Do you have a general mechanism to test that syzkaller will actually
> > > > pick up the kernel log splat of a new check?
> > >
> > > Yes. That's one of the most important and critical parts of syzkaller :)
> > > The tests for different types of bugs are here:
> > > https://github.com/google/syzkaller/tree/master/pkg/report/testdata/linux/report
> > >
> > > But have 3 for UBSAN, but they may be old and it would be useful to
> > > have 1 example crash per bug type:
> > >
> > > syzkaller$ grep UBSAN pkg/report/testdata/linux/report/*
> > > pkg/report/testdata/linux/report/40:TITLE: UBSAN: Undefined behaviour
> > > in drivers/usb/core/devio.c:LINE
> > > pkg/report/testdata/linux/report/40:[    4.556972] UBSAN: Undefined
> > > behaviour in drivers/usb/core/devio.c:1517:25
> > > pkg/report/testdata/linux/report/41:TITLE: UBSAN: Undefined behaviour
> > > in ./arch/x86/include/asm/atomic.h:LINE
> > > pkg/report/testdata/linux/report/41:[    3.805453] UBSAN: Undefined
> > > behaviour in ./arch/x86/include/asm/atomic.h:156:2
> > > pkg/report/testdata/linux/report/42:TITLE: UBSAN: Undefined behaviour
> > > in kernel/time/hrtimer.c:LINE
> > > pkg/report/testdata/linux/report/42:[   50.583499] UBSAN: Undefined
> > > behaviour in kernel/time/hrtimer.c:310:16
> > >
> > > One of them is incomplete and is parsed as "corrupted kernel output"
> > > (won't be reported):
> > > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/42
> > >
> > > Also I see that report parsing just takes the first line, which
> > > includes file name, which is suboptimal (too long, can't report 2 bugs
> > > in the same file). We seem to converge on "bug-type in function-name"
> > > format.
> > > The thing about bug titles is that it's harder to change them later.
> > > If syzbot already reported 100 bugs and we change titles, it will
> > > start re-reporting the old one after new names and the old ones will
> > > look stale, yet they still relevant, just detected under different
> > > name.
> > > So we also need to get this part right before enabling.
>
> It Sounds like instead of "UBSAN: Undefined behaviour in $file", UBSAN
> should report something like "UBSAN: $behavior in $file"?
>
> e.g.
> 40: UBSAN: bad shift in drivers/usb/core/devio.c:1517:25"
> 41: UBSAN: signed integer overflow in ./arch/x86/include/asm/atomic.h:156:2
>
> I'll add one for the bounds checker.
>
> How are these reports used? (And is there a way to check a live kernel
> crash? i.e. to tell syzkaller "echo ARRAY_BOUNDS >/.../lkdtm..." and
> generate a report?

I've collected the sample and added to syzkaller test base:
https://github.com/google/syzkaller/commit/76357d6f894431c00cc09cfc9e7474701a4b822a

I also filed https://github.com/google/syzkaller/issues/1523 for
enabling UBSAN on syzbot, let's move syzbot-related discussion there.

      parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-21 18:15 Kees Cook
2019-11-21 18:15 ` [PATCH v2 1/3] ubsan: Add trap instrumentation option Kees Cook
2019-11-21 18:15 ` [PATCH v2 2/3] ubsan: Split "bounds" checker from other options Kees Cook
2019-11-21 18:15 ` [PATCH v2 3/3] lkdtm/bugs: Add arithmetic overflow and array bounds checks Kees Cook
2019-11-22  9:07 ` [PATCH v2 0/3] ubsan: Split out bounds checker Dmitry Vyukov
2019-11-22 16:52   ` Kees Cook
2019-11-27  5:42   ` Kees Cook
2019-11-27  6:54     ` Dmitry Vyukov
2019-11-27  9:34       ` Dmitry Vyukov
2019-11-27 17:59         ` Kees Cook
2019-11-28 10:38           ` Dmitry Vyukov
2019-11-28 16:14             ` Qian Cai
2019-11-28 13:10           ` Dmitry Vyukov [this message]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CACT4Y+b7YtWw57C-1mv1z5bTSa9YpnwhKsgMAtpMuc6J8KXBUg@mail.gmail.com \
    --to=dvyukov@google.com \
    --cc=akpm@linux-foundation.org \
    --cc=ard.biesheuvel@linaro.org \
    --cc=aryabinin@virtuozzo.com \
    --cc=dan.carpenter@oracle.com \
    --cc=glider@google.com \
    --cc=gustavo@embeddedor.com \
    --cc=kasan-dev@googlegroups.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=lenaptr@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=syzkaller@googlegroups.com \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Kernel-hardening archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kernel-hardening/0 kernel-hardening/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kernel-hardening kernel-hardening/ https://lore.kernel.org/kernel-hardening \
		kernel-hardening@lists.openwall.com
	public-inbox-index kernel-hardening

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/com.openwall.lists.kernel-hardening


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git