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KEYS: DH: forbid using digest_null as the KDF hash

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Requesting "digest_null" in the keyctl_kdf_params caused an infinite
loop in kdf_ctr() because the "null" hash has a digest size of 0.  Fix
it by rejecting hash algorithms with a digest size of 0.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: James Morris <james.l.morris@oracle.com>
This commit is contained in:
Eric Biggers 2017-06-08 14:49:34 +01:00 committed by James Morris
parent 0620fddb56
commit bbe240454d
1 changed files with 11 additions and 1 deletions
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12
security/keys/dh.c
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@ -89,6 +89,7 @@ static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
struct crypto_shash *tfm;
struct kdf_sdesc *sdesc;
int size;
int err;
/* allocate synchronous hash */
tfm = crypto_alloc_shash(hashname, 0, 0);
@ -97,16 +98,25 @@ static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
return PTR_ERR(tfm);
}
err = -EINVAL;
if (crypto_shash_digestsize(tfm) == 0)
goto out_free_tfm;
err = -ENOMEM;
size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
sdesc = kmalloc(size, GFP_KERNEL);
if (!sdesc)
return -ENOMEM;
goto out_free_tfm;
sdesc->shash.tfm = tfm;
sdesc->shash.flags = 0x0;
*sdesc_ret = sdesc;
return 0;
out_free_tfm:
crypto_free_shash(tfm);
return err;
}
static void kdf_dealloc(struct kdf_sdesc *sdesc)