From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
peterz@infradead.org, mingo@kernel.org, luto@amacapital.net,
Scott Bauer <scott.bauer@intel.com>,
x86@kernel.org, Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com
Subject: Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume
Date: Thu, 1 Dec 2016 10:45:51 -0600 [thread overview]
Message-ID: <20161201164551.52xlcftamleam6vq@treble> (raw)
In-Reply-To: <20161201145821.imkcgizo4thmiei2@treble>
On Thu, Dec 01, 2016 at 08:58:21AM -0600, Josh Poimboeuf wrote:
> On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
> >
> >
> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> > > Resuming from a suspend operation is showing a KASAN false positive
> > > warning:
> > >
> >
> > > KASAN instrumentation poisons the stack when entering a function and
> > > unpoisons it when exiting the function. However, in the suspend path,
> > > some functions never return, so their stack never gets unpoisoned,
> > > resulting in stale KASAN shadow data which can cause false positive
> > > warnings like the one above.
> > >
> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > > ---
> > > arch/x86/kernel/acpi/sleep.c | 3 +++
> > > include/linux/kasan.h | 7 +++++++
> > > 2 files changed, 10 insertions(+)
> > >
> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> > > index 4858733..62bd046 100644
> > > --- a/arch/x86/kernel/acpi/sleep.c
> > > +++ b/arch/x86/kernel/acpi/sleep.c
> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> > > pause_graph_tracing();
> > > do_suspend_lowlevel();
> > > unpause_graph_tracing();
> > > +
> > > + kasan_unpoison_stack_below_sp();
> > > +
> >
> > I think this might be too late. We may hit stale poison in the first C function called
> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
>
> Yeah, I think you're right. Will spin a v2.
So I tried calling kasan_unpoison_task_stack_below() from
do_suspend_lowlevel(), but it hung on the resume. Presumably because
restore_processor_state() does some important setup which would be
needed before calling into kasan_unpoison_task_stack_below(). For
example, setting up the gs register. So it's a bit of a catch-22.
It could probably be fixed properly by rewriting do_suspend_lowlevel()
to call restore_processor_state() with the temporary stack before
switching to the original stack and doing the unpoison.
(And there are some other issues with do_suspend_lowlevel() and I'd love
to try taking a scalpel to it. But I have too many knives in the air
already to want to try to attempt that right now...)
Unless somebody else wants to take a stab at it, my original patch is
probably good enough for now, since restore_processor_state() doesn't
seem to be triggering any KASAN warnings.
--
Josh
next prev parent reply other threads:[~2016-12-01 16:45 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-29 18:13 BUG: KASAN: stack-out-of-bounds in unwind_get_return_address Scott Bauer
2016-11-30 18:35 ` Josh Poimboeuf
2016-11-30 19:02 ` Scott Bauer
2016-11-30 23:10 ` [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume Josh Poimboeuf
2016-12-01 9:05 ` Andrey Ryabinin
2016-12-01 14:58 ` Josh Poimboeuf
2016-12-01 16:45 ` Josh Poimboeuf [this message]
2016-12-01 16:51 ` Dmitry Vyukov
2016-12-01 17:13 ` Josh Poimboeuf
2016-12-01 17:27 ` Dmitry Vyukov
2016-12-01 17:34 ` Josh Poimboeuf
2016-12-01 17:47 ` Dmitry Vyukov
2016-12-01 17:56 ` Josh Poimboeuf
2016-12-01 20:31 ` [PATCH v2] " Josh Poimboeuf
2016-12-02 9:44 ` Dmitry Vyukov
2016-12-02 12:54 ` Pavel Machek
2016-12-02 13:41 ` Andrey Ryabinin
2016-12-02 14:01 ` Josh Poimboeuf
2016-12-02 14:02 ` Dmitry Vyukov
2016-12-02 14:42 ` [PATCH v3] " Josh Poimboeuf
2016-12-02 14:45 ` Andrey Ryabinin
2016-12-02 15:08 ` Josh Poimboeuf
2016-12-02 17:42 ` [PATCH v4] " Josh Poimboeuf
2016-12-02 20:55 ` Andrey Ryabinin
2016-12-02 21:09 ` Pavel Machek
2016-12-02 21:57 ` Josh Poimboeuf
2016-12-08 0:10 ` Rafael J. Wysocki
2016-12-01 14:04 ` [PATCH] " Rafael J. Wysocki
2016-12-01 16:53 ` Josh Poimboeuf
2016-12-01 17:05 ` Rafael J. Wysocki
2016-12-02 10:15 ` Ingo Molnar
Reply instructions:
You may reply publicly 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=20161201164551.52xlcftamleam6vq@treble \
--to=jpoimboe@redhat.com \
--cc=aryabinin@virtuozzo.com \
--cc=dvyukov@google.com \
--cc=glider@google.com \
--cc=kasan-dev@googlegroups.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mingo@kernel.org \
--cc=pavel@ucw.cz \
--cc=peterz@infradead.org \
--cc=rjw@rjwysocki.net \
--cc=scott.bauer@intel.com \
--cc=x86@kernel.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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).