[PATCH mm 1/2] kasan: don't use read-only static keys
elver at google.com
Wed Dec 9 13:49:36 EST 2020
On Wed, 9 Dec 2020 at 19:24, Andrey Konovalov <andreyknvl at google.com> wrote:
> __ro_after_init static keys are incompatible with usage in loadable kernel
> modules and cause crashes. Don't use those, use normal static keys.
> Signed-off-by: Andrey Konovalov <andreyknvl at google.com>
Reviewed-by: Marco Elver <elver at google.com>
> This fix can be squashed into
> "kasan: add and integrate kasan boot parameters".
> mm/kasan/hw_tags.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index c91f2c06ecb5..55bd6f09c70f 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -43,11 +43,11 @@ static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init;
> static enum kasan_arg_fault kasan_arg_fault __ro_after_init;
> /* Whether KASAN is enabled at all. */
Side-node: This appears to be just a bad interface; I think the macro
DEFINE_STATIC_KEY_FALSE_RO() is error-prone, if it can't be guaranteed
that this is always safe, since the presence of the macro encourages
its use and we'll inevitably run into this problem again.
DEFINE_STATIC_KEY_FALSE_RO() + EXPORT_SYMBOL() is an immediate bug.
Given its use has not increased substantially since its introduction,
it may be safer to consider its removal.
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