From: Siddhesh Poyarekar <siddhesh@gotplt.org>
To: Kees Cook <keescook@chromium.org>, linux-hardening@vger.kernel.org
Cc: Miguel Ojeda <ojeda@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Nick Desaulniers <ndesaulniers@google.com>,
Nathan Chancellor <nathan@kernel.org>, Tom Rix <trix@redhat.com>,
llvm@lists.linux.dev, Juergen Gross <jgross@suse.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] fortify: Use __builtin_dynamic_object_size() when available
Date: Wed, 21 Sep 2022 07:43:17 -0400 [thread overview]
Message-ID: <9d80e0a3-3fcc-0676-4529-79743f418557@gotplt.org> (raw)
In-Reply-To: <20220920192202.190793-5-keescook@chromium.org>
On 2022-09-20 15:22, Kees Cook wrote:
> Since the commits starting with c37495d6254c ("slab: add __alloc_size
> attributes for better bounds checking"), the compilers have runtime
> allocation size hints available in some places. This was immediately
> available to CONFIG_UBSAN_BOUNDS, but CONFIG_FORTIFY_SOURCE needed
> updating to explicitly make use the hints via the associated
> __builtin_dynamic_object_size() helper. Detect and use the builtin when
> it is available, increasing the accuracy of the mitigation. When runtime
> sizes are not available, __builtin_dynamic_object_size() falls back to
> __builtin_object_size(), leaving the existing bounds checking unchanged.
I don't know yet what the overhead is for __builtin_dynamic_object_size
vs __builtin_object_size, were you able to measure it somehow for the
kernel? If there's a significant tradeoff, it may make sense to provide
a user override.
Thanks,
Sid
next prev parent reply other threads:[~2022-09-21 11:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 19:21 [PATCH 0/4] fortify: Use __builtin_dynamic_object_size() when available Kees Cook
2022-09-20 19:21 ` [PATCH 1/4] x86/entry: Work around Clang __bdos() bug Kees Cook
2022-09-21 0:07 ` Boris Ostrovsky
2022-09-20 19:22 ` [PATCH 2/4] fortify: Explicitly check bounds are compile-time constants Kees Cook
2022-09-21 11:48 ` Siddhesh Poyarekar
2022-09-22 3:46 ` Kees Cook
2022-09-20 19:22 ` [PATCH 3/4] fortify: Convert to struct vs member helpers Kees Cook
2022-09-20 19:22 ` [PATCH 4/4] fortify: Use __builtin_dynamic_object_size() when available Kees Cook
2022-09-21 11:24 ` Miguel Ojeda
2022-09-21 11:43 ` Siddhesh Poyarekar [this message]
2022-09-22 3:33 ` Kees Cook
2022-09-22 14:45 ` Siddhesh Poyarekar
2022-11-22 10:20 ` Siddhesh Poyarekar
2022-11-23 5:15 ` Kees Cook
2022-11-23 15:29 ` Siddhesh Poyarekar
2023-01-13 15:59 ` linux-next - bxnt buffer overflow in strnlen Niklas Cassel
2023-01-13 16:08 ` linux-next - bnxt " Niklas Cassel
2023-01-13 22:44 ` Kees Cook
2023-01-16 10:56 ` Niklas Cassel
2022-09-22 20:26 ` [PATCH 0/4] fortify: Use __builtin_dynamic_object_size() when available Siddhesh Poyarekar
2022-09-23 0:20 ` Kees Cook
2022-09-23 0:55 ` Siddhesh Poyarekar
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