linux-kernel - Re: [PATCH v2 01/11] x86: kcov: disable instrumentation of arch/x86/kernel/tsc.c

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAG_fn=WYkgf3=9bTPJCpEq0HcxCtM-Kj8R-PQkjJgh4B4E16fA@mail.gmail.com>
Date: Mon, 30 Jun 2025 15:39:07 +0200
From: Alexander Potapenko <glider@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: quic_jiangenj@...cinc.com, linux-kernel@...r.kernel.org, 
	kasan-dev@...glegroups.com, Aleksandr Nogikh <nogikh@...gle.com>, 
	Andrey Konovalov <andreyknvl@...il.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Ingo Molnar <mingo@...hat.com>, Josh Poimboeuf <jpoimboe@...nel.org>, Marco Elver <elver@...gle.com>, 
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 01/11] x86: kcov: disable instrumentation of arch/x86/kernel/tsc.c

> Anyway, looking at kcov again, all the __sanitize_*() hooks seem to have
> check_kcov_mode(), which in turn has something like:
>
>  if (!in_task() ..)
>    return false;
>
> Which should be filtering out all these things, no? If this filter
> 'broken' ?

I think this is one of the cases where we are transitioning to the IRQ
context (so the coverage isn't really interesting for the fuzzer), but
still haven't bumped preempt_count.

In this particular case in_task() is 1, in_softirq_really() is 0, and
preempt_count() is 2.