linux-kernel - Re: [PATCH] Kconfig.debug: disable CONFIG_FRAME_WARN for KASAN_STACK && CC_IS

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Date:   Fri, 21 Apr 2023 16:30:40 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Tudor Ambarus" <tudor.ambarus@...aro.org>,
        "Nathan Chancellor" <nathan@...nel.org>,
        "Nick Desaulniers" <ndesaulniers@...gle.com>,
        "Tom Rix" <trix@...hat.com>,
        "Andrew Morton" <akpm@...ux-foundation.org>
Cc:     joneslee@...gle.com, "Peter Zijlstra" <peterz@...radead.org>,
        "Kees Cook" <keescook@...omium.org>,
        "Josh Poimboeuf" <jpoimboe@...nel.org>, zhaoyang.huang@...soc.com,
        "Liam R. Howlett" <liam.howlett@...cle.com>,
        "Randy Dunlap" <rdunlap@...radead.org>,
        "Geert Uytterhoeven" <geert+renesas@...der.be>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        "Mark Brown" <broonie@...nel.org>,
        "Dmitry Vyukov" <dvyukov@...gle.com>, nogikh@...gle.com
Subject: Re: [PATCH] Kconfig.debug: disable CONFIG_FRAME_WARN for KASAN_STACK &&
 CC_IS_CLANG by default

On Fri, Apr 21, 2023, at 15:01, Tudor Ambarus wrote:

> The conclusion is that when KASAN is enabled the stack usage increases a
> bit, but nothing unmanageable ~30-70 bytes, whereas when enabling
> KASAN_STACK the stack usage is excessive, from ~1.7K to ~5.8K for these
> cases.
>
> Disable CONFIG_FRAME_WARN for KASAN_STACK && CC_IS_CLANG by default.
> Adventurers can still override the default value by input prompt or
> explicit values in defconfigs in case they feel that some real warnings
> are missed.
>
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>

I think we are still better off with the warning enabled. When someone
really wants to run a kernel with KASAN_STACK enabled, they should have
a chance to see what they are getting into and not report any runtime
bugs that come from stack overflow. 

      Arnd