From a86003162138031137727147c9b642d99db434b1 Mon Sep 17 00:00:00 2001
From: Richard Levitte <levitte@openssl.org>
Date: Fri, 7 Dec 2018 09:26:04 +0100
Subject: [PATCH] Make EVP_PKEY_asn1_add0() stricter about its input

It turns out that the strictness that was implemented in
EVP_PKEY_asn1_new() (see Github openssl/openssl#6880) was badly placed
for some usages, and that it's better to do this check only when the
method is getting registered.

Fixes #7758

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7847)
---
 CHANGES                 |  3 +++
 crypto/asn1/ameth_lib.c | 28 ++++++++++++++++------------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/CHANGES b/CHANGES
index 49e2597e9e..1b6c91e04f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -9,6 +9,9 @@
 
  Changes between 1.1.1 and 3.0.0 [xx XXX xxxx]
 
+  *) Move strictness check from EVP_PKEY_asn1_new() to EVP_PKEY_asn1_add0().
+     [Richard Levitte]
+
   *) Change the license to the Apache License v2.0.
      [Richard Levitte]
 
diff --git a/crypto/asn1/ameth_lib.c b/crypto/asn1/ameth_lib.c
index d45b0cced4..b2bcd5acac 100644
--- a/crypto/asn1/ameth_lib.c
+++ b/crypto/asn1/ameth_lib.c
@@ -140,6 +140,22 @@ int EVP_PKEY_asn1_add0(const EVP_PKEY_ASN1_METHOD *ameth)
 {
     EVP_PKEY_ASN1_METHOD tmp = { 0, };
 
+    /*
+     * One of the following must be true:
+     *
+     * pem_str == NULL AND ASN1_PKEY_ALIAS is set
+     * pem_str != NULL AND ASN1_PKEY_ALIAS is clear
+     *
+     * Anything else is an error and may lead to a corrupt ASN1 method table
+     */
+    if (!((ameth->pem_str == NULL
+           && (ameth->pkey_flags & ASN1_PKEY_ALIAS) != 0)
+          || (ameth->pem_str != NULL
+              && (ameth->pkey_flags & ASN1_PKEY_ALIAS) == 0))) {
+        EVPerr(EVP_F_EVP_PKEY_ASN1_ADD0, ERR_R_PASSED_INVALID_ARGUMENT);
+        return 0;
+    }
+
     if (app_methods == NULL) {
         app_methods = sk_EVP_PKEY_ASN1_METHOD_new(ameth_cmp);
         if (app_methods == NULL)
@@ -216,18 +232,6 @@ EVP_PKEY_ASN1_METHOD *EVP_PKEY_asn1_new(int id, int flags,
             goto err;
     }
 
-    /*
-     * One of the following must be true:
-     *
-     * pem_str == NULL AND ASN1_PKEY_ALIAS is set
-     * pem_str != NULL AND ASN1_PKEY_ALIAS is clear
-     *
-     * Anything else is an error and may lead to a corrupt ASN1 method table
-     */
-    if (!((pem_str == NULL && (flags & ASN1_PKEY_ALIAS) != 0)
-          || (pem_str != NULL && (flags & ASN1_PKEY_ALIAS) == 0)))
-        goto err;
-
     if (pem_str) {
         ameth->pem_str = OPENSSL_strdup(pem_str);
         if (!ameth->pem_str)