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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id o27-v6sm19170233pfj.35.2018.07.16.21.21.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 16 Jul 2018 21:21:53 -0700 (PDT) From: Kees Cook To: Herbert Xu Cc: Kees Cook , Arnd Bergmann , Eric Biggers , "Gustavo A. R. Silva" , Alasdair Kergon , Giovanni Cabiddu , Lars Persson , Mike Snitzer , Rabin Vincent , Tim Chen , linux-crypto@vger.kernel.org, qat-linux@intel.com, dm-devel@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH v5 03/11] crypto: shash: Remove VLA usage Date: Mon, 16 Jul 2018 21:21:42 -0700 Message-Id: <20180717042150.37761-4-keescook@chromium.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180717042150.37761-1-keescook@chromium.org> References: <20180717042150.37761-1-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In the quest to remove all stack VLA usage from the kernel[1], this removes the VLAs in SHASH_DESC_ON_STACK (via crypto_shash_descsize()) by using the maximum allowable size (which is now more clearly captured in a macro). Similar limits are turned into macros as well. A review of existing sizes shows that SHA512_DIGEST_SIZE (64) is the largest digest size and that sizeof(struct sha3_state) (360) is the largest descriptor size. The corresponding maximums are reduced. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook --- crypto/shash.c | 6 +++--- include/crypto/hash.h | 6 +++++- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/crypto/shash.c b/crypto/shash.c index 5d732c6bb4b2..ab6902c6dae7 100644 --- a/crypto/shash.c +++ b/crypto/shash.c @@ -458,9 +458,9 @@ static int shash_prepare_alg(struct shash_alg *alg) { struct crypto_alg *base = &alg->base; - if (alg->digestsize > PAGE_SIZE / 8 || - alg->descsize > PAGE_SIZE / 8 || - alg->statesize > PAGE_SIZE / 8) + if (alg->digestsize > SHASH_MAX_DIGESTSIZE || + alg->descsize > SHASH_MAX_DESCSIZE || + alg->statesize > SHASH_MAX_STATESIZE) return -EINVAL; base->cra_type = &crypto_shash_type; diff --git a/include/crypto/hash.h b/include/crypto/hash.h index 76e432cab75d..ae14cc0e0cdb 100644 --- a/include/crypto/hash.h +++ b/include/crypto/hash.h @@ -151,9 +151,13 @@ struct shash_desc { void *__ctx[] CRYPTO_MINALIGN_ATTR; }; +#define SHASH_MAX_DIGESTSIZE 64 +#define SHASH_MAX_DESCSIZE 360 +#define SHASH_MAX_STATESIZE 512 + #define SHASH_DESC_ON_STACK(shash, ctx) \ char __##shash##_desc[sizeof(struct shash_desc) + \ - crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \ + SHASH_MAX_DESCSIZE] CRYPTO_MINALIGN_ATTR; \ struct shash_desc *shash = (struct shash_desc *)__##shash##_desc /** -- 2.17.1