linux-kernel - Re: [PATCH v2 2/3] arm64: lib: use C string functions with KASAN enabled.

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Message-ID: <20181029112034.GE14127@arm.com>
Date:   Mon, 29 Oct 2018 11:20:35 +0000
From:   Will Deacon <will.deacon@....com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        akpm@...ux-foundation.org
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Kyeongdon Kim <kyeongdon.kim@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 2/3] arm64: lib: use C string functions with KASAN
 enabled.

Hi Andrey, Andrew,

On Mon, Oct 29, 2018 at 11:16:15AM +0000, Andrey Ryabinin wrote:
> On 10/29/2018 01:29 PM, Will Deacon wrote:
> > On Thu, Sep 20, 2018 at 04:56:30PM +0300, Andrey Ryabinin wrote:
> >> ARM64 has asm implementation of memchr(), memcmp(), str[r]chr(),
> >> str[n]cmp(), str[n]len(). KASAN don't see memory accesses in asm
> >> code, thus it can potentially miss many bugs.
> >>
> >> Ifdef out __HAVE_ARCH_* defines of these functions when KASAN is
> >> enabled, so the generic implementations from lib/string.c will be used.
> >>
> >> We can't just remove the asm functions because efistub uses them.
> >> And we can't have two non-weak functions either, so declare the asm
> >> functions as weak.
> >>
> >> Reported-by: Kyeongdon Kim <kyeongdon.kim@....com>
> >> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> >> ---
> >> Changes since v1:
> >>  - Use WEAK() instead of .weak
> >>
> >>  arch/arm64/include/asm/string.h | 14 ++++++++------
> >>  arch/arm64/kernel/arm64ksyms.c  |  7 +++++--
> >>  arch/arm64/lib/memchr.S         |  2 +-
> >>  arch/arm64/lib/memcmp.S         |  2 +-
> >>  arch/arm64/lib/strchr.S         |  2 +-
> >>  arch/arm64/lib/strcmp.S         |  2 +-
> >>  arch/arm64/lib/strlen.S         |  2 +-
> >>  arch/arm64/lib/strncmp.S        |  2 +-
> >>  arch/arm64/lib/strnlen.S        |  2 +-
> >>  arch/arm64/lib/strrchr.S        |  2 +-
> >>  10 files changed, 21 insertions(+), 16 deletions(-)
> > 
> > Acked-by: Will Deacon <will.deacon@....com>
> > 
> > Please post these again after the merge window and we'll figure out how to
> > get them queued.
> 
> Andrew sent these patches to Linus couple days ago, so they are in tree
> already.

Oh, good thing I was happy with them in the end, then!

> Something went wrong with mail notification though. I didn't even realize
> that they were in -mm tree, because I didn't receive the usual 'the patch
> has been added to -mm tree' email.  But I did receive email that was sent
> to Linus.

Yeah, strange. I usually see the notifications from Andrew.

> Also there was no you or Catalin in Cc tags in 2,3 patches, and in the
> first patch, the Cc tags were corrupted:

:/

Andrew -- have we broken your scripts somehow, or is this just a one-off
for these patches?

Thanks,

Will

> From: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Subject: include/linux/linkage.h: align weak symbols
> 
> Since WEAK() supposed to be used instead of ENTRY() to define weak
> symbols, but unlike ENTRY() it doesn't have ALIGN directive.  It seems
> there is no actual reason to not have, so let's add ALIGN to WEAK() too.
> 
> Link: http://lkml.kernel.org/r/20180920135631.23833-1-aryabinin@virtuozzo.com
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Will Deacon <will.deacon@....com>, Catalin Marinas <catalin.marinas@....com>
> Cc: Kyeongdon Kim <kyeongdon.kim@....com>
> Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Cc: Alexander Potapenko <glider@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>