From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: [PATCH v6 01/18] crypto: xcbc: Remove VLA usage Date: Tue, 24 Jul 2018 09:49:19 -0700 Message-ID: <20180724164936.37477-2-keescook@chromium.org> References: <20180724164936.37477-1-keescook@chromium.org> Cc: Kees Cook , Arnd Bergmann , Eric Biggers , "Gustavo A. R. Silva" , Alasdair Kergon , Rabin Vincent , Tim Chen , "Rafael J. Wysocki" , Pavel Machek , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Philipp Reisner , Lars Ellenberg , Jens Axboe , Giovanni Cabiddu , Mike Snitzer , Paul Mackerras , Greg Kroah-Hartman , David Howells Return-path: In-Reply-To: <20180724164936.37477-1-keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-crypto.vger.kernel.org In the quest to remove all stack VLA usage from the kernel[1], this uses the maximum blocksize and adds a sanity check. For xcbc, the blocksize must always be 16, so use that, since it's already being enforced during instantiation. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org Signed-off-by: Kees Cook --- crypto/xcbc.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/crypto/xcbc.c b/crypto/xcbc.c index 25c75af50d3f..c055f57fab11 100644 --- a/crypto/xcbc.c +++ b/crypto/xcbc.c @@ -57,15 +57,17 @@ struct xcbc_desc_ctx { u8 ctx[]; }; +#define XCBC_BLOCKSIZE 16 + static int crypto_xcbc_digest_setkey(struct crypto_shash *parent, const u8 *inkey, unsigned int keylen) { unsigned long alignmask = crypto_shash_alignmask(parent); struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent); - int bs = crypto_shash_blocksize(parent); u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1); int err = 0; - u8 key1[bs]; + u8 key1[XCBC_BLOCKSIZE]; + int bs = sizeof(key1); if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen))) return err; @@ -212,7 +214,7 @@ static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb) return PTR_ERR(alg); switch(alg->cra_blocksize) { - case 16: + case XCBC_BLOCKSIZE: break; default: goto out_put_alg; -- 2.17.1