linux-kernel - Re: [PATCH v5] kprobes: unpoison stack in jprobe

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Message-ID: <20161016070130.GA2569@gmail.com>
Date:   Sun, 16 Oct 2016 09:01:30 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Eugene Surovegin <surovegin@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Alexander Potapenko <glider@...gle.com>,
        Will Deacon <will.deacon@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [PATCH v5] kprobes: unpoison stack in jprobe_return() for KASAN


* Dmitry Vyukov <dvyukov@...gle.com> wrote:

> On Sat, Oct 15, 2016 at 8:30 AM, Ingo Molnar <mingo@...nel.org> wrote:
> >
> > * Dmitry Vyukov <dvyukov@...gle.com> wrote:
> >
> >> KASAN stack instrumentation poisons stack redzones on function entry
> >> and unpoisons them on function exit. If a function exits abnormally
> >> (e.g. with a longjmp like jprobe_return()), stack redzones are left
> >> poisoned. Later this leads to random KASAN false reports.
> >>
> >> Unpoison stack redzones in the frames we are going to jump over
> >> before doing actual longjmp in jprobe_return().
> >
> > Does this affect any other architecture besides arm64? If not then it might make
> > the most sense to merge this via the arm64 tree.
> 
> 
> This is mostly for x86_64. This patch fixes KASAN false positives
> related to jprobe on x86_64.

Indeed: I should have read the patch beyond the diffstat.

> Arm64 related part is only a function rename. As I introduce a
> function similar to an existing one, Mark asked to me rename the
> existing function to clarify the difference between the two.

Fair enough!

Thanks,

	Ingo