linux-kernel - Re: [PATCH] arm64: increase stack size for KASAN

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Message-ID: <CAK8P3a20kRDrkS1YFLp6cYeKcUoC9s+O_tnYNbKEMWGukia1Tg@mail.gmail.com>
Date:   Tue, 11 Dec 2018 13:42:24 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     cai@....pw
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux-MM <linux-mm@...ck.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: increase stack size for KASAN_EXTRA

On Fri, Dec 7, 2018 at 11:35 PM Qian Cai <cai@....pw> wrote:
>
> If the kernel is configured with KASAN_EXTRA, the stack size is
> increasted significantly due to enable this option will set
> -fstack-reuse to "none" in GCC [1]. As the results, it could trigger
> stack overrun quite often with 32k stack size compiled using GCC 8. For
> example, this reproducer

>
> size
> 7536 shrink_inactive_list
> 7440 shrink_page_list
> 6560 fscache_stats_show
> 3920 jbd2_journal_commit_transaction
> 3216 try_to_unmap_one
> 3072 migrate_page_move_mapping
> 3584 migrate_misplaced_transhuge_page
> 3920 ip_vs_lblcr_schedule
> 4304 lpfc_nvme_info_show
> 3888 lpfc_debugfs_nvmestat_data.constprop
>
> There are other 49 functions are over 2k in size while compiling kernel
> with "-Wframe-larger-than=" on this machine. Hence, it is too much work
> to change Makefiles for each object to compile without
> -fsanitize-address-use-after-scope individually.
>
> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715#c23

Could you clarify: are the numbers you see with or without the bugfix
from that bugzilla?

       Arnd