On Fri, Jul 19, 2019 at 1:03 PM Arnd Bergmann wrote:
>
> asan-stack mode still uses dangerously large kernel stacks of
> tens of kilobytes in some drivers, and it does not seem that anyone
> is working on the clang bug.
Acked-by: Nick Desaulniers
>
> Turn it off for all clang versions to prevent users from
> accidentally enabling it once they update to clang-9, and
> to help automated build testing with clang-9.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=38809
> Fixes: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier")
> Signed-off-by: Arnd Bergmann
> ---
> v2: disable the feature for all clang versions, not just 9 and below.
> ---
> lib/Kconfig.kasan | 11 +--
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 4fafba1a923b..7fa97a8b5717 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -106,7 +106,6 @@ endchoice
>
> config KASAN_STACK_ENABLE
> bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG &&
> !COMPILE_TEST
> - default !(CLANG_VERSION < 9)
> depends on KASAN
> help
> The LLVM stack address sanitizer has a know problem that
> @@ -115,11 +114,11 @@ config KASAN_STACK_ENABLE
> Disabling asan-stack makes it safe to run kernels build
> with clang-8 with KASAN enabled, though it loses some of
> the functionality.
> - This feature is always disabled when compile-testing with clang-8
> - or earlier to avoid cluttering the output in stack overflow
> - warnings, but clang-8 users can still enable it for builds without
> - CONFIG_COMPILE_TEST. On gcc and later clang versions it is
> - assumed to always be safe to use and enabled by default.
> + This feature is always disabled when compile-testing with clang
> + to avoid cluttering the output in stack overflow warnings,
> + but clang users can still enable it for builds without
> + CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe
> + to use and enabled by default.
>
> config KASAN_STACK
> int
> --
> 2.20.0
>
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--
Thanks,
~Nick Desaulniers
