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Message-ID: <ZN9HL5qI5yt/hFnc@gondor.apana.org.au>
Date: Fri, 18 Aug 2023 18:25:51 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>,
"David S. Miller" <davem@...emloft.net>,
Nicolas Ferre <nicolas.ferre@...rochip.com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Claudiu Beznea <claudiu.beznea@...on.dev>,
Ayush Sawal <ayush.sawal@...lsio.com>,
Ryan Wanner <Ryan.Wanner@...rochip.com>,
Yangtao Li <frank.li@...o.com>, Wang Ming <machel@...o.com>,
Sergiu Moga <sergiu.moga@...rochip.com>,
Gaosheng Cui <cuigaosheng1@...wei.com>,
linux-crypto@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] crypto: drivers - avoid memcpy size warning
On Fri, Aug 11, 2023 at 03:46:33PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> Some configurations with gcc-12 or gcc-13 produce a warning for the source
> and destination of a memcpy() in atmel_sha_hmac_compute_ipad_hash() potentially
> overlapping:
>
> In file included from include/linux/string.h:254,
> from drivers/crypto/atmel-sha.c:15:
> drivers/crypto/atmel-sha.c: In function 'atmel_sha_hmac_compute_ipad_hash':
> include/linux/fortify-string.h:57:33: error: '__builtin_memcpy' accessing 129 or more bytes at offsets 408 and 280 overlaps 1 or more bytes at offset 408 [-Werror=restrict]
> 57 | #define __underlying_memcpy __builtin_memcpy
> | ^
> include/linux/fortify-string.h:648:9: note: in expansion of macro '__underlying_memcpy'
> 648 | __underlying_##op(p, q, __fortify_size); \
> | ^~~~~~~~~~~~~
> include/linux/fortify-string.h:693:26: note: in expansion of macro '__fortify_memcpy_chk'
> 693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
> | ^~~~~~~~~~~~~~~~~~~~
> drivers/crypto/atmel-sha.c:1773:9: note: in expansion of macro 'memcpy'
> 1773 | memcpy(hmac->opad, hmac->ipad, bs);
> | ^~~~~~
>
> The same thing happens in two more drivers that have the same logic:
>
> drivers/crypto/chelsio/chcr_algo.c: In function 'chcr_ahash_setkey':
> include/linux/fortify-string.h:57:33: error: '__builtin_memcpy' accessing 129 or more bytes at offsets 260 and 132 overlaps 1 or more bytes at offset 260 [-Werror=restrict]
> drivers/crypto/bcm/cipher.c: In function 'ahash_hmac_setkey':
> include/linux/fortify-string.h:57:33: error: '__builtin_memcpy' accessing between 129 and 4294967295 bytes at offsets 840 and 712 overlaps between 1 and 4294967167 bytes at offset 840 [-Werror=restrict]
>
> I don't think it can actually happen because the size is strictly bounded
> to the available block sizes, at most 128 bytes, though inlining decisions
> could lead gcc to not see that.
>
> Use the unsafe_memcpy() helper instead of memcpy(), with the only difference
> being that this skips the hardening checks that produce the warning.
>
> Suggested-by: Herbert Xu <herbert@...dor.apana.org.au>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
> drivers/crypto/atmel-sha.c | 3 ++-
> drivers/crypto/bcm/cipher.c | 3 ++-
> drivers/crypto/chelsio/chcr_algo.c | 3 ++-
> 3 files changed, 6 insertions(+), 3 deletions(-)
Patch applied. Thanks.
--
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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