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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id p11-v6sm72711991pfj.72.2018.07.16.21.21.57 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 16 Jul 2018 21:21:58 -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 11/11] crypto: skcipher: Remove VLA usage for SKCIPHER_REQUEST_ON_STACK Date: Mon, 16 Jul 2018 21:21:50 -0700 Message-Id: <20180717042150.37761-12-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 caps the skcipher request size similar to other limits and adds a sanity check at registration. Looking at instrumented tcrypt output, the largest is for lrw: crypt: testing lrw(aes) crypto_skcipher_set_reqsize: 8 crypto_skcipher_set_reqsize: 88 crypto_skcipher_set_reqsize: 472 [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook --- include/crypto/internal/skcipher.h | 1 + include/crypto/skcipher.h | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h index e42f7063f245..5035482cbe68 100644 --- a/include/crypto/internal/skcipher.h +++ b/include/crypto/internal/skcipher.h @@ -130,6 +130,7 @@ static inline struct crypto_skcipher *crypto_spawn_skcipher( static inline void crypto_skcipher_set_reqsize( struct crypto_skcipher *skcipher, unsigned int reqsize) { + BUG_ON(reqsize > SKCIPHER_MAX_REQSIZE); skcipher->reqsize = reqsize; } diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h index 2f327f090c3e..c48e194438cf 100644 --- a/include/crypto/skcipher.h +++ b/include/crypto/skcipher.h @@ -139,9 +139,11 @@ struct skcipher_alg { struct crypto_alg base; }; +#define SKCIPHER_MAX_REQSIZE 472 + #define SKCIPHER_REQUEST_ON_STACK(name, tfm) \ char __##name##_desc[sizeof(struct skcipher_request) + \ - crypto_skcipher_reqsize(tfm)] CRYPTO_MINALIGN_ATTR; \ + SKCIPHER_MAX_REQSIZE] CRYPTO_MINALIGN_ATTR; \ struct skcipher_request *name = (void *)__##name##_desc /** -- 2.17.1