From: Lance Yang <lance.yang@linux.dev>
To: dev.jain@arm.com
Cc: ryabinin.a.a@gmail.com, akpm@linux-foundation.org,
corbet@lwn.net, glider@google.com, andreyknvl@gmail.com,
dvyukov@google.com, vincenzo.frascino@arm.com,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, skhan@linuxfoundation.org,
workflows@vger.kernel.org, linux-doc@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com,
anshuman.khandual@arm.com, kaleshsingh@google.com,
21cnbao@gmail.com, david@kernel.org, will@kernel.org,
catalin.marinas@arm.com, Lance Yang <lance.yang@linux.dev>
Subject: Re: [RFC PATCH 0/2] kasan: hw_tags: Add option to tag only at allocation time
Date: Sat, 13 Jun 2026 14:06:37 +0800 [thread overview]
Message-ID: <20260613060637.40039-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20260612044425.763060-1-dev.jain@arm.com>
On Fri, Jun 12, 2026 at 04:44:22AM +0000, Dev Jain wrote:
>Introduce a boot option to tag only at allocation time of the objects. This
>reduces KASAN MTE overhead, the tradeoff being reduced ability of
>catching bugs.
>
>Now, when a memory object will be freed, it will retain the random tag it
>had at allocation time. This compromises on catching UAF bugs, till the
>time the object is not reallocated, at which point it will have a new
>random tag.
>
>Hence, not catching "use-after-free-before-reallocation" and not catching
>"double-free" will be the compromise for reduced KASAN overhead.
Hmm ... do we also need to teach the KASAN KUnit tests about this mode?
With kasan.tag_only_on_alloc=on, free-time poisoning is skipped, so
some UAF and double-free reports are skipped on purpose, but the tests
still expect them :)
Cheers, Lance
prev parent reply other threads:[~2026-06-13 6:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 4:44 [RFC PATCH 0/2] kasan: hw_tags: Add option to tag only at allocation time Dev Jain
2026-06-12 4:44 ` [RFC PATCH 1/2] kasan: hw_tags: Use KASAN_PAGE_REDZONE for vmalloc redzoning Dev Jain
2026-06-12 4:44 ` [RFC PATCH 2/2] kasan: hw_tags: Add boot option to elide free time poisoning Dev Jain
2026-06-13 0:23 ` Isaac Manjarres
2026-06-13 0:16 ` [RFC PATCH 0/2] kasan: hw_tags: Add option to tag only at allocation time Isaac Manjarres
2026-06-13 6:06 ` Lance Yang [this message]
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