From: Will Deacon <will.deacon@arm.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org, Qian Cai <cai@lca.pw>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH] kasan: Remove use after scope bugs detection.
Date: Wed, 16 Jan 2019 16:47:13 +0000 [thread overview]
Message-ID: <20190116164712.GB1910@brain-police> (raw)
In-Reply-To: <20190111185842.13978-1-aryabinin@virtuozzo.com>
On Fri, Jan 11, 2019 at 09:58:42PM +0300, Andrey Ryabinin wrote:
> Use after scope bugs detector seems to be almost entirely useless
> for the linux kernel. It exists over two years, but I've seen only
> one valid bug so far [1]. And the bug was fixed before it has been
> reported. There were some other use-after-scope reports, but they
> were false-positives due to different reasons like incompatibility
> with structleak plugin.
>
> This feature significantly increases stack usage, especially with
> GCC < 9 version, and causes a 32K stack overflow. It probably
> adds performance penalty too.
>
> Given all that, let's remove use-after-scope detector entirely.
>
> While preparing this patch I've noticed that we mistakenly enable
> use-after-scope detection for clang compiler regardless of
> CONFIG_KASAN_EXTRA setting. This is also fixed now.
>
> [1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com>
>
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Qian Cai <cai@lca.pw>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/include/asm/memory.h | 4 ----
> lib/Kconfig.debug | 1 -
> lib/Kconfig.kasan | 10 ----------
> lib/test_kasan.c | 24 ------------------------
> mm/kasan/generic.c | 19 -------------------
> mm/kasan/generic_report.c | 3 ---
> mm/kasan/kasan.h | 3 ---
> scripts/Makefile.kasan | 5 -----
> scripts/gcc-plugins/Kconfig | 4 ----
> 9 files changed, 73 deletions(-)
For the arm64 part:
Acked-by: Will Deacon <will.deacon@arm.com>
but I defer to you and Dmitry as to whether or not you go ahead with this.
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
linux-mm@kvack.org, Qian Cai <cai@lca.pw>,
Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] kasan: Remove use after scope bugs detection.
Date: Wed, 16 Jan 2019 16:47:13 +0000 [thread overview]
Message-ID: <20190116164712.GB1910@brain-police> (raw)
In-Reply-To: <20190111185842.13978-1-aryabinin@virtuozzo.com>
On Fri, Jan 11, 2019 at 09:58:42PM +0300, Andrey Ryabinin wrote:
> Use after scope bugs detector seems to be almost entirely useless
> for the linux kernel. It exists over two years, but I've seen only
> one valid bug so far [1]. And the bug was fixed before it has been
> reported. There were some other use-after-scope reports, but they
> were false-positives due to different reasons like incompatibility
> with structleak plugin.
>
> This feature significantly increases stack usage, especially with
> GCC < 9 version, and causes a 32K stack overflow. It probably
> adds performance penalty too.
>
> Given all that, let's remove use-after-scope detector entirely.
>
> While preparing this patch I've noticed that we mistakenly enable
> use-after-scope detection for clang compiler regardless of
> CONFIG_KASAN_EXTRA setting. This is also fixed now.
>
> [1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com>
>
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Qian Cai <cai@lca.pw>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/include/asm/memory.h | 4 ----
> lib/Kconfig.debug | 1 -
> lib/Kconfig.kasan | 10 ----------
> lib/test_kasan.c | 24 ------------------------
> mm/kasan/generic.c | 19 -------------------
> mm/kasan/generic_report.c | 3 ---
> mm/kasan/kasan.h | 3 ---
> scripts/Makefile.kasan | 5 -----
> scripts/gcc-plugins/Kconfig | 4 ----
> 9 files changed, 73 deletions(-)
For the arm64 part:
Acked-by: Will Deacon <will.deacon@arm.com>
but I defer to you and Dmitry as to whether or not you go ahead with this.
Will
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next prev parent reply other threads:[~2019-01-16 16:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-11 18:58 [PATCH] kasan: Remove use after scope bugs detection Andrey Ryabinin
2019-01-11 18:58 ` Andrey Ryabinin
2019-01-14 13:24 ` Dmitry Vyukov
2019-01-14 13:24 ` Dmitry Vyukov
2019-01-14 13:24 ` Dmitry Vyukov
2019-01-14 16:08 ` Andrey Ryabinin
2019-01-14 16:08 ` Andrey Ryabinin
2019-01-16 16:47 ` Will Deacon [this message]
2019-01-16 16:47 ` Will Deacon
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