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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id x65-v6sm6984082pfk.140.2018.07.24.09.49.45 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 24 Jul 2018 09:49:47 -0700 (PDT) From: Kees Cook To: Herbert Xu Date: Tue, 24 Jul 2018 09:49:25 -0700 Message-Id: <20180724164936.37477-8-keescook@chromium.org> In-Reply-To: <20180724164936.37477-1-keescook@chromium.org> References: <20180724164936.37477-1-keescook@chromium.org> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 24 Jul 2018 16:49:52 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 24 Jul 2018 16:49:52 +0000 (UTC) for IP:'209.85.215.196' DOMAIN:'mail-pg1-f196.google.com' HELO:'mail-pg1-f196.google.com' FROM:'keescook@chromium.org' RCPT:'' X-RedHat-Spam-Score: -0.131 (DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_PASS) 209.85.215.196 mail-pg1-f196.google.com 209.85.215.196 mail-pg1-f196.google.com X-Scanned-By: MIMEDefang 2.78 on 10.5.110.27 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-loop: dm-devel@redhat.com Cc: Giovanni Cabiddu , Mike Snitzer , "Gustavo A. R. Silva" , linux-wireless@vger.kernel.org, Will Deacon , linux-kernel@vger.kernel.org, David Howells , dm-devel@redhat.com, Jia-Ju Bai , Paul Mackerras , Pavel Machek , "H. Peter Anvin" , linux-afs@lists.infradead.org, Alasdair Kergon , Kees Cook , devel@driverdev.osuosl.org, x86@kernel.org, qat-linux@intel.com, Ingo Molnar , Eric Biggers , Geert Uytterhoeven , drbd-dev@lists.linbit.com, Rabin Vincent , Arnd Bergmann , Tudor-Dan Ambarus , linux-block@vger.kernel.org, Josh Poimboeuf , Thomas Gleixner , Lars Ellenberg , Jens Axboe , Andrew Morton , Greg Kroah-Hartman , linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Philipp Reisner , linux-crypto@vger.kernel.org, linux-ppp@vger.kernel.org, Johannes Berg , Tim Chen , netdev@vger.kernel.org, David Woodhouse Subject: [dm-devel] [PATCH v6 07/18] crypto: shash: Remove VLA usage in unaligned hashing X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 24 Jul 2018 16:50:10 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP In the quest to remove all stack VLA usage from the kernel[1], this uses the newly defined max alignment to perform unaligned hashing to avoid VLAs, and drops the helper function while adding sanity checks on the resulting buffer sizes. Additionally, the __aligned_largest macro is removed since this helper was the only user. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook --- crypto/shash.c | 27 ++++++++++++++++----------- include/linux/compiler-gcc.h | 1 - 2 files changed, 16 insertions(+), 12 deletions(-) diff --git a/crypto/shash.c b/crypto/shash.c index 86d76b5c626c..d21f04d70dce 100644 --- a/crypto/shash.c +++ b/crypto/shash.c @@ -73,13 +73,6 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key, } EXPORT_SYMBOL_GPL(crypto_shash_setkey); -static inline unsigned int shash_align_buffer_size(unsigned len, - unsigned long mask) -{ - typedef u8 __aligned_largest u8_aligned; - return len + (mask & ~(__alignof__(u8_aligned) - 1)); -} - static int shash_update_unaligned(struct shash_desc *desc, const u8 *data, unsigned int len) { @@ -88,11 +81,17 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data, unsigned long alignmask = crypto_shash_alignmask(tfm); unsigned int unaligned_len = alignmask + 1 - ((unsigned long)data & alignmask); - u8 ubuf[shash_align_buffer_size(unaligned_len, alignmask)] - __aligned_largest; + /* + * We cannot count on __aligned() working for large values: + * https://patchwork.kernel.org/patch/9507697/ + */ + u8 ubuf[MAX_ALGAPI_ALIGNMASK * 2]; u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1); int err; + if (WARN_ON(buf + unaligned_len > ubuf + sizeof(ubuf))) + return -EINVAL; + if (unaligned_len > len) unaligned_len = len; @@ -124,11 +123,17 @@ static int shash_final_unaligned(struct shash_desc *desc, u8 *out) unsigned long alignmask = crypto_shash_alignmask(tfm); struct shash_alg *shash = crypto_shash_alg(tfm); unsigned int ds = crypto_shash_digestsize(tfm); - u8 ubuf[shash_align_buffer_size(ds, alignmask)] - __aligned_largest; + /* + * We cannot count on __aligned() working for large values: + * https://patchwork.kernel.org/patch/9507697/ + */ + u8 ubuf[MAX_ALGAPI_ALIGNMASK + HASH_MAX_DIGESTSIZE]; u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1); int err; + if (WARN_ON(buf + ds > ubuf + sizeof(ubuf))) + return -EINVAL; + err = shash->final(desc, buf); if (err) goto out; diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index f1a7492a5cc8..1f1cdef36a82 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -125,7 +125,6 @@ */ #define __pure __attribute__((pure)) #define __aligned(x) __attribute__((aligned(x))) -#define __aligned_largest __attribute__((aligned)) #define __printf(a, b) __attribute__((format(printf, a, b))) #define __scanf(a, b) __attribute__((format(scanf, a, b))) #define __attribute_const__ __attribute__((__const__))