Re: [PATCH] fs/select: rework stack allocation hack for clang

[Kees Cook <keescook@chromium.org>]

On Fri, Feb 16, 2024 at 09:23:34PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> A while ago, we changed the way that select() and poll() preallocate
> a temporary buffer just under the size of the static warning limit of
> 1024 bytes, as clang was frequently going slightly above that limit.
> 
> The warnings have recently returned and I took another look. As it turns
> out, clang is not actually inherently worse at reserving stack space,
> it just happens to inline do_select() into core_sys_select(), while gcc
> never inlines it.
> 
> Annotate do_select() to never be inlined and in turn remove the special
> case for the allocation size. This should give the same behavior for
> both clang and gcc all the time and once more avoids those warnings.
> 
> Fixes: ad312f95d41c ("fs/select: avoid clang stack usage warning")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook