[PATCH v2 03/11] crypto: shash: Remove VLA usage
From: Kees Cook <hidden>
Date: 2018-06-25 21:13:06
Also in:
dm-devel, lkml
Subsystem:
crypto api, the rest · Maintainers:
Herbert Xu, "David S. Miller", Linus Torvalds
In the quest to remove all stack VLA usage from the kernel[1], this removes the VLAs in SHASH_DESC_ON_STACK (via crypto_shash_descsize()) by using the maximum allowable size (which is now more clearly captured in a macro). Similar limits are turned into macros as well. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-crypto@vger.kernel.org Signed-off-by: Kees Cook <redacted> --- crypto/shash.c | 6 +++--- include/crypto/hash.h | 6 +++++- 2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/crypto/shash.c b/crypto/shash.c
index 5d732c6bb4b2..ab6902c6dae7 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c@@ -458,9 +458,9 @@ static int shash_prepare_alg(struct shash_alg *alg) { struct crypto_alg *base = &alg->base; - if (alg->digestsize > PAGE_SIZE / 8 || - alg->descsize > PAGE_SIZE / 8 || - alg->statesize > PAGE_SIZE / 8) + if (alg->digestsize > SHASH_MAX_DIGESTSIZE || + alg->descsize > SHASH_MAX_DESCSIZE || + alg->statesize > SHASH_MAX_STATESIZE) return -EINVAL; base->cra_type = &crypto_shash_type;
diff --git a/include/crypto/hash.h b/include/crypto/hash.h
index 76e432cab75d..804e87a9510e 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h@@ -151,9 +151,13 @@ struct shash_desc { void *__ctx[] CRYPTO_MINALIGN_ATTR; }; +#define SHASH_MAX_DIGESTSIZE 512 +#define SHASH_MAX_DESCSIZE 512 +#define SHASH_MAX_STATESIZE 512 + #define SHASH_DESC_ON_STACK(shash, ctx) \ char __##shash##_desc[sizeof(struct shash_desc) + \ - crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \ + SHASH_MAX_DESCSIZE] CRYPTO_MINALIGN_ATTR; \ struct shash_desc *shash = (struct shash_desc *)__##shash##_desc /**
--
2.17.1