Don't assume the type we read was the type we expected
authorMatt Caswell <matt@openssl.org>
Wed, 30 Oct 2019 13:23:18 +0000 (13:23 +0000)
committerMatt Caswell <matt@openssl.org>
Mon, 4 Nov 2019 12:49:19 +0000 (12:49 +0000)
i2v_GENERAL_NAME and GENERAL_NAME_print were assuming that the type of
of a GENERAL_NAME (OTHERNAME) that we read in was the type we expected
it to be. If its something else then this can cause unexpected
behaviour. In the added fuzz test case an OOB read was occurring.

This issue was recently added by commit 4baee2d.

Credit to OSSFuzz for finding this issue.

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10300)

crypto/x509/v3_alt.c
fuzz/corpora/x509/9901a721c7fe85b8208198cc5e77ac719f592577 [new file with mode: 0644]

index 1feb2d6..f31b884 100644 (file)
@@ -86,19 +86,31 @@ STACK_OF(CONF_VALUE) *i2v_GENERAL_NAME(X509V3_EXT_METHOD *method,
     case GEN_OTHERNAME:
         switch (OBJ_obj2nid(gen->d.otherName->type_id)) {
         case NID_id_on_SmtpUTF8Mailbox:
-            if (!X509V3_add_value_uchar("othername: SmtpUTF8Mailbox:", gen->d.otherName->value->value.utf8string->data, &ret))
+            if (gen->d.otherName->value->type != V_ASN1_UTF8STRING
+                    || !X509V3_add_value_uchar("othername: SmtpUTF8Mailbox:",
+                            gen->d.otherName->value->value.utf8string->data,
+                            &ret))
                 return NULL;
             break;
         case NID_XmppAddr:
-            if (!X509V3_add_value_uchar("othername: XmppAddr:", gen->d.otherName->value->value.utf8string->data, &ret))
+            if (gen->d.otherName->value->type != V_ASN1_UTF8STRING
+                    || !X509V3_add_value_uchar("othername: XmppAddr:",
+                            gen->d.otherName->value->value.utf8string->data,
+                            &ret))
                 return NULL;
             break;
         case NID_SRVName:
-            if (!X509V3_add_value_uchar("othername: SRVName:", gen->d.otherName->value->value.ia5string->data, &ret))
+            if (gen->d.otherName->value->type != V_ASN1_IA5STRING
+                    || !X509V3_add_value_uchar("othername: SRVName:",
+                            gen->d.otherName->value->value.ia5string->data,
+                            &ret))
                 return NULL;
             break;
         case NID_ms_upn:
-            if (!X509V3_add_value_uchar("othername: UPN:", gen->d.otherName->value->value.utf8string->data, &ret))
+            if (gen->d.otherName->value->type != V_ASN1_UTF8STRING
+                    || !X509V3_add_value_uchar("othername: UPN:",
+                            gen->d.otherName->value->value.utf8string->data,
+                            &ret))
                 return NULL;
             break;
         default:
@@ -174,21 +186,36 @@ STACK_OF(CONF_VALUE) *i2v_GENERAL_NAME(X509V3_EXT_METHOD *method,
 int GENERAL_NAME_print(BIO *out, GENERAL_NAME *gen)
 {
     unsigned char *p;
-    int i;
+    int i, nid;
+
     switch (gen->type) {
     case GEN_OTHERNAME:
-        switch (OBJ_obj2nid(gen->d.otherName->type_id)) {
+        nid = OBJ_obj2nid(gen->d.otherName->type_id);
+        /* Validate the types are as we expect before we use them */
+        if ((nid == NID_SRVName
+             && gen->d.otherName->value->type != V_ASN1_IA5STRING)
+                || (nid != NID_SRVName
+                    && gen->d.otherName->value->type != V_ASN1_UTF8STRING)) {
+            BIO_printf(out, "othername:<unsupported>");
+            break;
+        }
+
+        switch (nid) {
         case NID_id_on_SmtpUTF8Mailbox:
-            BIO_printf(out, "othername:SmtpUTF8Mailbox:%s", gen->d.otherName->value->value.utf8string->data);
+            BIO_printf(out, "othername:SmtpUTF8Mailbox:%s",
+                       gen->d.otherName->value->value.utf8string->data);
             break;
         case NID_XmppAddr:
-            BIO_printf(out, "othername:XmppAddr:%s", gen->d.otherName->value->value.utf8string->data);
+            BIO_printf(out, "othername:XmppAddr:%s",
+                       gen->d.otherName->value->value.utf8string->data);
             break;
         case NID_SRVName:
-            BIO_printf(out, "othername:SRVName:%s", gen->d.otherName->value->value.ia5string->data);
+            BIO_printf(out, "othername:SRVName:%s",
+                       gen->d.otherName->value->value.ia5string->data);
             break;
         case NID_ms_upn:
-            BIO_printf(out, "othername:UPN:%s", gen->d.otherName->value->value.utf8string->data);
+            BIO_printf(out, "othername:UPN:%s",
+                       gen->d.otherName->value->value.utf8string->data);
             break;
         default:
             BIO_printf(out, "othername:<unsupported>");
diff --git a/fuzz/corpora/x509/9901a721c7fe85b8208198cc5e77ac719f592577 b/fuzz/corpora/x509/9901a721c7fe85b8208198cc5e77ac719f592577
new file mode 100644 (file)
index 0000000..40369cd
Binary files /dev/null and b/fuzz/corpora/x509/9901a721c7fe85b8208198cc5e77ac719f592577 differ