Re: [PATCH RFC bpf-next 1/8] kasan: expose generic kasan helpers

Andrey Konovalov
2026-04-19T21:49:11Z

On Tue, Apr 14, 2026 at 5:58 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> I think we're talking past each other.
> We're not interested in KASAN_SW_TAGS or KASAN_HW_TAGS.
> We're not going to modify arm64 JIT at all.
>
> This is purely KASAN_GENRIC and only on x86-64.
> JIT will emit exactly what compilers emit for generic
> which is __asan_load/store. This is as stable ABI as it can get
> and we don't want to deviate from it.

OK, I supposed that's fair. You did throw me off point with your
performance comment. But if you decide to add SW_TAGS support at some
point, I think this discussion needs to be revisited.

But please add a comment saying that those functions are only exposed
for BPF JIT and they are not supposed to be used by other parts of the
kernel. And in case you do end up adding a new config option, guard
the public declarations by a corresponding ifdef.

> The goal here is to find bugs in the verifier.
> If something got past it, that shouldn't have,
> kasan generic on x86-64 is enough.

FWIW, I suspect HW_TAGS KASAN already just works with JITed BPF code.