linux-kernel - Re: [PATCH] ARM: head-common.S: Clear lr before jumping to start

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]

Message-ID: <CAMuHMdWJKQb5JY+diH=7dqNuypkPUqBeOEPSLOrfrnbfh2siRQ@mail.gmail.com>
Date:   Tue, 3 Oct 2017 20:11:59 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Nicolas Pitre <nicolas.pitre@...aro.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Russell King <linux@...linux.org.uk>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Chris Brandt <Chris.Brandt@...esas.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: head-common.S: Clear lr before jumping to start_kernel()

On Tue, Oct 3, 2017 at 5:37 PM, Nicolas Pitre <nicolas.pitre@...aro.org> wrote:
> On Tue, 3 Oct 2017, Geert Uytterhoeven wrote:
>
>> If CONFIG_DEBUG_LOCK_ALLOC=y, the kernel log is spammed with a few
>> hundred identical messages:
>>
>>     unwind: Unknown symbol address c0800300
>>     unwind: Index not found c0800300
>>
>> c0800300 is the return address from the last subroutine call (to
>> __memzero()) in __mmap_switched().  Apparently having this address in
>> the link register confuses the unwinder.
>>
>> To fix this, reset the link register to zero before jumping to
>> start_kernel().
>>
>> Fixes: 9520b1a1b5f7a348 ("ARM: head-common.S: speed up startup code")
>> Suggested-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
>
> Good! This fixes another similar case I had but I didn't come around to
> look at closely yet.
>
> Acked-by: Nicolas Pitre <nico@...aro.org>

Thanks!

> Please send it to RMK's patch system.

Done (I hope so ;-)

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds