net: sctp: sctp_setsockopt_auth_key: use kzfree instead of kfree

[ Upstream commit 6ba542a2 ]

In sctp_setsockopt_auth_key, we create a temporary copy of the user
passed shared auth key for the endpoint or association and after
internal setup, we free it right away. Since it's sensitive data, we
should zero out the key before returning the memory back to the
allocator. Thus, use kzfree instead of kfree, just as we do in
sctp_auth_key_put().
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/sctp/socket.c

@@ -3375,7 +3375,7 @@ static int sctp_setsockopt_auth_key(struct sock *sk,
 
 	ret = sctp_auth_set_key(sctp_sk(sk)->ep, asoc, authkey);
 out:
-	kfree(authkey);
+	kzfree(authkey);
 	return ret;
 }