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Commit f805f59d authored by Kees Cook's avatar Kees Cook Committed by Herbert Xu
Browse files

crypto: mxs-dcp - Remove VLA usage of skcipher 

In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com



Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 28874f26

drivers/crypto/mxs-dcp.c

+10 −11
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ struct dcp_async_ctx { 
	unsigned int			hot:1;



	/* Crypto-specific context */

	struct crypto_skcipher		*fallback;

	struct crypto_sync_skcipher	*fallback;

	unsigned int			key_len;

	uint8_t				key[AES_KEYSIZE_128];

};
@@ -376,10 +376,10 @@ static int mxs_dcp_block_fallback(struct ablkcipher_request *req, int enc) 
{

	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);

	struct dcp_async_ctx *ctx = crypto_ablkcipher_ctx(tfm);

	SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);

	SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);

	int ret;



	skcipher_request_set_tfm(subreq, ctx->fallback);

	skcipher_request_set_sync_tfm(subreq, ctx->fallback);

	skcipher_request_set_callback(subreq, req->base.flags, NULL, NULL);

	skcipher_request_set_crypt(subreq, req->src, req->dst,

				   req->nbytes, req->info);
@@ -460,16 +460,16 @@ static int mxs_dcp_aes_setkey(struct crypto_ablkcipher *tfm, const u8 *key, 
	 * but is supported by in-kernel software implementation, we use

	 * software fallback.

	 */

	crypto_skcipher_clear_flags(actx->fallback, CRYPTO_TFM_REQ_MASK);

	crypto_skcipher_set_flags(actx->fallback,

	crypto_sync_skcipher_clear_flags(actx->fallback, CRYPTO_TFM_REQ_MASK);

	crypto_sync_skcipher_set_flags(actx->fallback,

				  tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);



	ret = crypto_skcipher_setkey(actx->fallback, key, len);

	ret = crypto_sync_skcipher_setkey(actx->fallback, key, len);

	if (!ret)

		return 0;



	tfm->base.crt_flags &= ~CRYPTO_TFM_RES_MASK;

	tfm->base.crt_flags |= crypto_skcipher_get_flags(actx->fallback) &

	tfm->base.crt_flags |= crypto_sync_skcipher_get_flags(actx->fallback) &

			       CRYPTO_TFM_RES_MASK;



	return ret;
@@ -478,11 +478,10 @@ static int mxs_dcp_aes_setkey(struct crypto_ablkcipher *tfm, const u8 *key, 
static int mxs_dcp_aes_fallback_init(struct crypto_tfm *tfm)

{

	const char *name = crypto_tfm_alg_name(tfm);

	const uint32_t flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK;

	struct dcp_async_ctx *actx = crypto_tfm_ctx(tfm);

	struct crypto_skcipher *blk;

	struct crypto_sync_skcipher *blk;



	blk = crypto_alloc_skcipher(name, 0, flags);

	blk = crypto_alloc_sync_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);

	if (IS_ERR(blk))

		return PTR_ERR(blk);
@@ -495,7 +494,7 @@ static void mxs_dcp_aes_fallback_exit(struct crypto_tfm *tfm) 
{

	struct dcp_async_ctx *actx = crypto_tfm_ctx(tfm);



	crypto_free_skcipher(actx->fallback);

	crypto_free_sync_skcipher(actx->fallback);

}



/*