From: Dave Hansen <dave.hansen@intel.com>
To: Borislav Petkov <bp@alien8.de>, Ihor Solodrai <ihor.solodrai@linux.dev>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
bpf@vger.kernel.org, kasan-dev@googlegroups.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Andrey Konovalov <andreyknvl@gmail.com>
Subject: Re: [PATCH v1] kasan: Fix false-positive wild-memory-access on x86 under 5-level paging
Date: Thu, 18 Jun 2026 11:12:09 -0700 [thread overview]
Message-ID: <3207a706-354c-4e9d-ba53-dded1abb1842@intel.com> (raw)
In-Reply-To: <20260618170913.GBajQmOQyOiBLqopUl@fat_crate.local>
On 6/18/26 10:09, Borislav Petkov wrote:
> On Wed, Jun 17, 2026 at 03:13:33PM -0700, Ihor Solodrai wrote:
>> So my question to maintainers is what approach seems best?
> The CPUID stuff is being rewritten currently and it should address your issue
> too. If not, then we need to rewrite it better.
>
> Can you reproduce with this set applied ontop:
>
> https://lore.kernel.org/r/20260528153923.403473-1-darwi@linutronix.de
Thinking about this a bit more... If Ahmed's series does fix this, I
think it will be accidental. It still uses identify_cpu() and also does
a memset() of the new c->cpuid structure in addition to the old
c->x86_capability structure.
I'm not knocking Ahmed's series by any means. It just probably won't fix
this issue.
In a perfect world early_identify_cpu() and identify_cpu() would either
get consolidated into one thing. Or at least become two discrete things
that initialize two completely disjoint sets of data. That way,
identify_cpu() wouldn't memset() anything.
Isn't that the _real_ fix? Instead of trying to hide the inconsistency
when good data is blown away, we stop blowing it away in the first place?
next prev parent reply other threads:[~2026-06-18 18:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-10 17:56 [PATCH v1] kasan: Fix false-positive wild-memory-access on x86 under 5-level paging Ihor Solodrai
2026-06-10 18:39 ` Andrey Konovalov
2026-06-10 21:55 ` Ihor Solodrai
2026-06-12 16:30 ` Kiryl Shutsemau
2026-06-12 19:42 ` Ihor Solodrai
2026-06-17 22:13 ` Ihor Solodrai
2026-06-18 16:55 ` Andrey Ryabinin
2026-06-18 17:09 ` Borislav Petkov
2026-06-18 18:12 ` Dave Hansen [this message]
2026-06-18 18:38 ` Borislav Petkov
2026-06-23 0:29 ` Ihor Solodrai
2026-06-23 0:35 ` Ihor Solodrai
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