crypto: hash - Fixed digest size check
The digest size check on hash algorithms is incorrect. It's
perfectly valid for hash algorithms to have a digest length
longer than their block size. For example crc32c has a block
size of 1 and a digest size of 4. Rather than having it lie
about its block size, this patch fixes the checks to do what
they really should which is to bound the digest size so that
code placing the digest on the stack continue to work.
HMAC however still needs to check this as it's only defined
for such algorithms.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/hmac.c b/crypto/hmac.c
index 14c6351..7ff2d6a 100644
--- a/crypto/hmac.c
+++ b/crypto/hmac.c
@@ -226,6 +226,7 @@
struct crypto_instance *inst;
struct crypto_alg *alg;
int err;
+ int ds;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH);
if (err)
@@ -236,6 +237,13 @@
if (IS_ERR(alg))
return ERR_CAST(alg);
+ inst = ERR_PTR(-EINVAL);
+ ds = (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+ CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :
+ alg->cra_digest.dia_digestsize;
+ if (ds > alg->cra_blocksize)
+ goto out_put_alg;
+
inst = crypto_alloc_instance("hmac", alg);
if (IS_ERR(inst))
goto out_put_alg;
@@ -246,14 +254,10 @@
inst->alg.cra_alignmask = alg->cra_alignmask;
inst->alg.cra_type = &crypto_hash_type;
- inst->alg.cra_hash.digestsize =
- (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
- CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :
- alg->cra_digest.dia_digestsize;
+ inst->alg.cra_hash.digestsize = ds;
inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) +
- ALIGN(inst->alg.cra_blocksize * 2 +
- inst->alg.cra_hash.digestsize,
+ ALIGN(inst->alg.cra_blocksize * 2 + ds,
sizeof(void *));
inst->alg.cra_init = hmac_init_tfm;