On 24 July 2018 at 18:49, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > > 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 > [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@xxxxxxxxxxxxxx > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > 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 >
