linux-kernel - Re: [PATCH -tip V2] [BUGFIX] kprobes/x86: Do not jump-optimize kprobes on irq entry code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 25 Jul 2017 12:40:05 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Francis Deslauriers <francis.deslauriers@...icios.com>,
        mathieu.desnoyers@...icios.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Ananth N Mavinakayanahalli <ananth@...ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -tip V2] [BUGFIX] kprobes/x86: Do not jump-optimize
 kprobes on irq entry code


* Masami Hiramatsu <mhiramat@...nel.org> wrote:

> Since the kernel segment registers are not prepared at the
> entry of irq-entry code, if a kprobe on such code is
> jump-optimized, accessing per-cpu variables may cause
> kernel panic.
> However, if the kprobe is not optimized, it kicks int3
> exception and set segment registers correctly.
> 
> This checks probe-address and if it is in irq-entry code,
> it prohibits optimizing such kprobes. This means we can
> continuously probing such interrupt handlers by kprobes
> but it is not optimized anymore.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> Reported-by: Francis Deslauriers <francis.deslauriers@...icios.com>
> Tested-by: Francis Deslauriers <francis.deslauriers@...icios.com>
> ---
>  Changes in V2:
>   - Make changes in kprobe/opt.c local, not involving unwind,
>     since it requires CONFIG_FRAME_POINTER=y (Thanks Mathieu!)

This patch doesn't even build on x86-64 defconfig ...

arch/x86/kernel/kprobes/opt.c: In function ‘can_optimize’:
arch/x86/kernel/kprobes/opt.c:259:32: error: ‘__irqentry_text_start’ undeclared 
(first use in this function)
      ((paddr >= (unsigned long)__irqentry_text_start) &&
                                ^~~~~~~~~~~~~~~~~~~~~

Thanks,

	Ingo