From: Catalin Marinas <catalin.marinas@arm.com>
To: Peter Collingbourne <pcc@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <kees@kernel.org>, Andy Shevchenko <andy@kernel.org>,
Andrey Konovalov <andreyknvl@gmail.com>,
Mark Rutland <mark.rutland@arm.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org
Subject: Re: [PATCH v5 1/2] string: Add load_unaligned_zeropad() code path to sized_strscpy()
Date: Thu, 3 Apr 2025 10:47:28 +0100 [thread overview]
Message-ID: <Z-5ZMOqhca_Z6FV7@arm.com> (raw)
In-Reply-To: <20250403000703.2584581-2-pcc@google.com>
On Wed, Apr 02, 2025 at 05:06:59PM -0700, Peter Collingbourne wrote:
> The call to read_word_at_a_time() in sized_strscpy() is problematic
> with MTE because it may trigger a tag check fault when reading
> across a tag granule (16 bytes) boundary. To make this code
> MTE compatible, let's start using load_unaligned_zeropad()
> on architectures where it is available (i.e. architectures that
> define CONFIG_DCACHE_WORD_ACCESS). Because load_unaligned_zeropad()
> takes care of page boundaries as well as tag granule boundaries,
> also disable the code preventing crossing page boundaries when using
> load_unaligned_zeropad().
>
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> Link: https://linux-review.googlesource.com/id/If4b22e43b5a4ca49726b4bf98ada827fdf755548
> Fixes: 94ab5b61ee16 ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS")
> Cc: stable@vger.kernel.org
Up to you if you want to keep the panic behaviour on unmapped pages.
Either way:
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
next prev parent reply other threads:[~2025-04-03 10:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-03 0:06 [PATCH v5 0/2] string: Add load_unaligned_zeropad() code path to sized_strscpy() Peter Collingbourne
2025-04-03 0:06 ` [PATCH v5 1/2] " Peter Collingbourne
2025-04-03 9:47 ` Catalin Marinas [this message]
2025-04-03 0:07 ` [PATCH v5 2/2] kasan: Add strscpy() test to trigger tag fault on arm64 Peter Collingbourne
2025-04-03 9:47 ` Catalin Marinas
2025-04-03 17:20 ` [PATCH v5 0/2] string: Add load_unaligned_zeropad() code path to sized_strscpy() Kees Cook
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