crypto: cbc - Ensure statesize is zero

The cbc template should not be applied on stream ciphers, especially
ones that have internal state.  Enforce this by checking the state
size when the instance is created.

Reported-by: syzbot+050eeedd6c285d8c42f2@syzkaller.appspotmail.com
Fixes: 47309ea1 ("crypto: arc4 - Add internal state")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/cbc.c

@@ -148,6 +148,9 @@ static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	if (!is_power_of_2(inst->alg.co.base.cra_blocksize))
 		goto out_free_inst;
 
+	if (inst->alg.co.statesize)
+		goto out_free_inst;
+
 	inst->alg.encrypt = crypto_cbc_encrypt;
 	inst->alg.decrypt = crypto_cbc_decrypt;