evm: check hash algorithm passed to init_desc()

This patch prevents memory access beyond the evm_tfm array by checking the
validity of the index (hash algorithm) passed to init_desc(). The hash
algorithm can be arbitrarily set if the security.ima xattr type is not
EVM_XATTR_HMAC.

Fixes: 5feeb61183 ("evm: Allow non-SHA1 digital signatures")
Signed-off-by: Roberto Sassu <[email protected]>
Cc: [email protected]
Signed-off-by: Mimi Zohar <[email protected]>
This commit is contained in:
Roberto Sassu 2019-05-29 15:30:33 +02:00 • committed by Mimi Zohar
commit 221be106d7

View file

@ -89,6 +89,9 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
tfm = &hmac_tfm;
algo = evm_hmac;
} else {
if (hash_algo >= HASH_ALGO__LAST)
return ERR_PTR(-EINVAL);
tfm = &evm_tfm[hash_algo];
algo = hash_algo_name[hash_algo];
}