Re: [PATCH v6 17/18] crypto: ccm: Remove VLA usage
From: Ard Biesheuvel <hidden>
Date: 2018-07-24 16:57:48
Also in:
dm-devel, linux-block, linux-crypto, linux-pm, linux-wireless, lkml
On 24 July 2018 at 18:49, Kees Cook [off-list ref] wrote:
From: Ard Biesheuvel <redacted> In the quest to remove all stack VLA usage from the kernel[1], this drops AHASH_REQUEST_ON_STACK by preallocated the ahash request area with the skcipher area (which are not used at the same time).
-EGRAMMAR
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[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Ard Biesheuvel <redacted> Signed-off-by: Kees Cook <redacted> --- crypto/ccm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)diff --git a/crypto/ccm.c b/crypto/ccm.c index 0a083342ec8c..b242fd0d3262 100644 --- a/crypto/ccm.c +++ b/crypto/ccm.c@@ -50,7 +50,10 @@ struct crypto_ccm_req_priv_ctx { u32 flags; struct scatterlist src[3]; struct scatterlist dst[3]; - struct skcipher_request skreq; + union { + struct ahash_request ahreq; + struct skcipher_request skreq; + }; }; struct cbcmac_tfm_ctx {@@ -181,7 +184,7 @@ static int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain, struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req); struct crypto_aead *aead = crypto_aead_reqtfm(req); struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead); - AHASH_REQUEST_ON_STACK(ahreq, ctx->mac); + struct ahash_request *ahreq = &pctx->ahreq; unsigned int assoclen = req->assoclen; struct scatterlist sg[3]; u8 *odata = pctx->odata;@@ -427,7 +430,7 @@ static int crypto_ccm_init_tfm(struct crypto_aead *tfm) crypto_aead_set_reqsize( tfm, align + sizeof(struct crypto_ccm_req_priv_ctx) + - crypto_skcipher_reqsize(ctr)); + max(crypto_ahash_reqsize(mac), crypto_skcipher_reqsize(ctr))); return 0; --2.17.1