linux-hardening - Re: UBSAN: annotation to skip sanitization in variable that will wrap

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Message-ID: <1019eec3-3b1c-42b4-9649-65f58284bfec@kernel.dk>
Date: Thu, 15 Aug 2024 12:40:12 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Breno Leitao <leitao@...ian.org>, Justin Stitt <justinstitt@...gle.com>
Cc: kees@...nel.org, elver@...gle.com, andreyknvl@...il.com,
 ryabinin.a.a@...il.com, kasan-dev@...glegroups.com,
 linux-hardening@...r.kernel.org, asml.silence@...il.com,
 netdev@...r.kernel.org
Subject: Re: UBSAN: annotation to skip sanitization in variable that will wrap

On 8/15/24 11:58 AM, Breno Leitao wrote:
>> 1) There exists some new-ish macros in overflow.h that perform
>> wrapping arithmetic without triggering sanitizer splats -- check out
>> the wrapping_* suite of macros.
> 
> do they work for atomic? I suppose we also need to have them added to
> this_cpu_add(), this_cpu_sub() helpers.

I don't think so, it's the bias added specifically to the atomic_long_t
that's the issue with the percpu refs.

-- 
Jens Axboe