KEYS: DH: forbid using digest_null as the KDF hash
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>
diff --git a/security/keys/dh.c b/security/keys/dh.c
index e603bd9..8abc70e 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -89,6 +89,7 @@
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 @@
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)