From 84743d3e7fae623c0a20bd727ec6e8c4031bf42f Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Wed, 11 Nov 2020 16:12:58 +0000
Subject: [PATCH] Correctly compare EdiPartyName in GENERAL_NAME_cmp()

If a GENERAL_NAME field contained EdiPartyName data then it was
incorrectly being handled as type "other". This could lead to a
segmentation fault.

Many thanks to David Benjamin from Google for reporting this issue.

CVE-2020-1971
---
 crypto/x509v3/v3_genn.c | 45 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 42 insertions(+), 3 deletions(-)

--- a/crypto/x509v3/v3_genn.c
+++ b/crypto/x509v3/v3_genn.c
@@ -108,6 +108,37 @@ GENERAL_NAME *GENERAL_NAME_dup(GENERAL_N
                                     (char *)a);
 }
 
+static int edipartyname_cmp(const EDIPARTYNAME *a, const EDIPARTYNAME *b)
+{
+    int res;
+
+    if (a == NULL || b == NULL) {
+        /*
+         * Shouldn't be possible in a valid GENERAL_NAME, but we handle it
+         * anyway. OTHERNAME_cmp treats NULL != NULL so we do the same here
+         */
+        return -1;
+    }
+    if (a->nameAssigner == NULL && b->nameAssigner != NULL)
+        return -1;
+    if (a->nameAssigner != NULL && b->nameAssigner == NULL)
+        return 1;
+    /* If we get here then both have nameAssigner set, or both unset */
+    if (a->nameAssigner != NULL) {
+        res = ASN1_STRING_cmp(a->nameAssigner, b->nameAssigner);
+        if (res != 0)
+            return res;
+    }
+    /*
+     * partyName is required, so these should never be NULL. We treat it in
+     * the same way as the a == NULL || b == NULL case above
+     */
+    if (a->partyName == NULL || b->partyName == NULL)
+        return -1;
+
+    return ASN1_STRING_cmp(a->partyName, b->partyName);
+}
+
 /* Returns 0 if they are equal, != 0 otherwise. */
 int GENERAL_NAME_cmp(GENERAL_NAME *a, GENERAL_NAME *b)
 {
@@ -117,8 +148,11 @@ int GENERAL_NAME_cmp(GENERAL_NAME *a, GE
         return -1;
     switch (a->type) {
     case GEN_X400:
+        result = ASN1_TYPE_cmp(a->d.x400Address, b->d.x400Address);
+        break;
+
     case GEN_EDIPARTY:
-        result = ASN1_TYPE_cmp(a->d.other, b->d.other);
+        result = edipartyname_cmp(a->d.ediPartyName, b->d.ediPartyName);
         break;
 
     case GEN_OTHERNAME:
@@ -165,8 +199,11 @@ void GENERAL_NAME_set0_value(GENERAL_NAM
 {
     switch (type) {
     case GEN_X400:
+        a->d.x400Address = value;
+        break;
+
     case GEN_EDIPARTY:
-        a->d.other = value;
+        a->d.ediPartyName = value;
         break;
 
     case GEN_OTHERNAME:
@@ -200,8 +237,10 @@ void *GENERAL_NAME_get0_value(GENERAL_NA
         *ptype = a->type;
     switch (a->type) {
     case GEN_X400:
+        return a->d.x400Address;
+
     case GEN_EDIPARTY:
-        return a->d.other;
+        return a->d.ediPartyName;
 
     case GEN_OTHERNAME:
         return a->d.otherName;