crypto: ecdh - fix 'ecdh_init'

mainline inclusion
from mainline-master
commit 8fd28fa5
category: bugfix
bugzilla: 173981
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fd28fa5046b377039d5bbc0ab2f625dec703980

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NIST P192 is not unregistered if failed to register NIST P256,
actually it need to unregister the algorithms already registered.
Signed-off-by: NHui Tang <tanghui20@huawei.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NMingqiang Ling <lingmingqiang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

crypto/ecdh.c

@@ -183,7 +183,16 @@ static int ecdh_init(void)
 	ret = crypto_register_kpp(&ecdh_nist_p192);
 	ecdh_nist_p192_registered = ret == 0;
 
-	return crypto_register_kpp(&ecdh_nist_p256);
+	ret = crypto_register_kpp(&ecdh_nist_p256);
+	if (ret)
+		goto nist_p256_error;
+
+	return 0;
+
+nist_p256_error:
+	if (ecdh_nist_p192_registered)
+		crypto_unregister_kpp(&ecdh_nist_p192);
+	return ret;
 }
 
 static void ecdh_exit(void)