From: Conor Dooley <conor@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: "Paul Walmsley" <paul.walmsley@sifive.com>,
"Thorsten Leemhuis" <linux@leemhuis.info>,
"Joan Bruguera Micó" <joanbrugueram@gmail.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Conor Dooley" <conor.dooley@microchip.com>,
"Nick Desaulniers" <ndesaulniers@google.com>,
"Alyssa Ross" <hi@alyssa.is>,
"Heiko Stuebner" <heiko.stuebner@vrull.eu>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-riscv@lists.infradead.org,
"Andrew Jones" <ajones@ventanamicro.com>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2] riscv/purgatory: Do not use fortified string functions
Date: Thu, 1 Jun 2023 18:34:20 +0100 [thread overview]
Message-ID: <20230601-connected-unbolted-cf708c6da4a1@spud> (raw)
In-Reply-To: <20230601160025.gonna.868-kees@kernel.org>
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On Thu, Jun 01, 2023 at 09:00:28AM -0700, Kees Cook wrote:
> With the addition of -fstrict-flex-arrays=3, struct sha256_state's
> trailing array is no longer ignored by CONFIG_FORTIFY_SOURCE:
>
> struct sha256_state {
> u32 state[SHA256_DIGEST_SIZE / 4];
> u64 count;
> u8 buf[SHA256_BLOCK_SIZE];
> };
>
> This means that the memcpy() calls with "buf" as a destination in
> sha256.c's code will attempt to perform run-time bounds checking, which
> could lead to calling missing functions, specifically a potential
> WARN_ONCE, which isn't callable from purgatory.
>
> Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
> Closes: https://lore.kernel.org/lkml/175578ec-9dec-7a9c-8d3a-43f24ff86b92@leemhuis.info/
> Bisected-by: "Joan Bruguera Micó" <joanbrugueram@gmail.com>
> Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3")
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Albert Ou <aou@eecs.berkeley.edu>
> Cc: Masahiro Yamada <masahiroy@kernel.org>
> Cc: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Thanks for the quick update Kees,
Conor.
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next prev parent reply other threads:[~2023-06-01 17:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-01 16:00 [PATCH v2] riscv/purgatory: Do not use fortified string functions Kees Cook
2023-06-01 17:34 ` Conor Dooley [this message]
2023-06-01 18:27 ` Kees Cook
2023-06-01 20:17 ` Palmer Dabbelt
2023-06-01 20:31 ` Kees Cook
2023-06-01 21:04 ` Palmer Dabbelt
2023-06-01 20:20 ` patchwork-bot+linux-riscv
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