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Thu, 09 Sep 2021 04:46:12 -0700 (PDT) MIME-Version: 1.0 References: <20210909104925.809674-1-elver@google.com> In-Reply-To: <20210909104925.809674-1-elver@google.com> From: Marco Elver Date: Thu, 9 Sep 2021 13:46:01 +0200 Message-ID: Subject: Re: [PATCH] kasan: double -Wframe-larger-than threshold if KASAN To: elver@google.com, Andrew Morton Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Arnd Bergmann , Christoph Hellwig , Guenter Roeck , Nathan Chancellor , Nick Desaulniers , Aleksandr Nogikh , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Taras Madan , linux-mm@kvack.org, llvm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=HocwwpvI; spf=pass (imf06.hostedemail.com: domain of elver@google.com designates 209.85.210.53 as permitted sender) smtp.mailfrom=elver@google.com; dmarc=pass (policy=reject) header.from=google.com X-Stat-Signature: tfm7xjzd3un946bqecifzeqwgnnwk8ri X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B0EDB801A8A7 X-HE-Tag: 1631187973-335680 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 9 Sept 2021 at 12:49, Marco Elver wrote: > All architectures at least double stack size when using one of the KASAN > software modes that rely on compiler instrumentation. > > Until now, warnings emitted by -Wframe-larger-than could easily be > ignored, as we would still get a working kernel. > > However, with the introduction of -Werror (CONFIG_WERROR=y), it makes > sense to at least double the -Wframe-larger-than threshold for > software-based KASAN modes to reflect the already increased stack sizes > when building a kernel with KASAN enabled. > > Link: https://lkml.kernel.org/r/YTbOs13waorzamZ6@Ryzen-9-3900X.localdomain > Signed-off-by: Marco Elver FWIW, there's still no consensus if this is what we want, and the discussion continues at: https://lkml.kernel.org/r/CANpmjNPBdx4b7bp=reNJPMzSNetdyrk+503_1LLoxNMYwUhSHg@mail.gmail.com > --- > lib/Kconfig.debug | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index ed4a31e34098..2055bbb6724a 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -345,6 +345,8 @@ endif # DEBUG_INFO > config FRAME_WARN > int "Warn for stack frames larger than" > range 0 8192 > + default 4096 if 64BIT && (KASAN_GENERIC || KASAN_SW_TAGS) > + default 2048 if !64BIT && (KASAN_GENERIC || KASAN_SW_TAGS) > default 2048 if GCC_PLUGIN_LATENT_ENTROPY > default 1536 if (!64BIT && PARISC) > default 1024 if (!64BIT && !PARISC) > -- > 2.33.0.153.gba50c8fa24-goog >