Add fuzz-der-cert driver with dictionary and corpus

Dictionary extracted from ASN1 constants. Corpus extracted from unit tests.
NOTE: Corpus is *not* yet minimized.

BUILD.gn

@@ -55,6 +55,7 @@ if (current_toolchain != "${dir_pw_toolchain}/default:default") {
     group("fuzz_tests") {
       deps = [
         "${chip_root}/src/credentials/tests:fuzz-chip-cert",
+        "${chip_root}/src/credentials/tests:fuzz-der-cert",
         "${chip_root}/src/lib/core/tests:fuzz-tlv-reader",
         "${chip_root}/src/lib/dnssd/minimal_mdns/tests:fuzz-minmdns-packet-parsing",
         "${chip_root}/src/lib/format/tests:fuzz-payload-decoder",

integrations/fuzz/fuzz-der-cert.dict

@@ -0,0 +1,36 @@
+# ASN1 constants extracted from src/lib/asn1/ASN1.h
+
+# ASN1TagClasses
+kASN1TagClass_Universal       = "\x00"
+kASN1TagClass_Application     = "\x40"
+kASN1TagClass_ContextSpecific = "\x80"
+kASN1TagClass_Private         = "\xC0"
+
+# ASN1UniversalTags
+kASN1UniversalTag_Boolean         = "\x01"
+kASN1UniversalTag_Integer         = "\x02"
+kASN1UniversalTag_BitString       = "\x03"
+kASN1UniversalTag_OctetString     = "\x04"
+kASN1UniversalTag_Null            = "\x05"
+kASN1UniversalTag_ObjectId        = "\x06"
+kASN1UniversalTag_ObjectDesc      = "\x07"
+kASN1UniversalTag_External        = "\x08"
+kASN1UniversalTag_Real            = "\x09"
+kASN1UniversalTag_Enumerated      = "\x0A"
+kASN1UniversalTag_UTF8String      = "\x0C"
+kASN1UniversalTag_Sequence        = "\x10"
+kASN1UniversalTag_Set             = "\x11"
+kASN1UniversalTag_NumericString   = "\x12"
+kASN1UniversalTag_PrintableString = "\x13"
+kASN1UniversalTag_T61String       = "\x14"
+kASN1UniversalTag_VideotexString  = "\x15"
+kASN1UniversalTag_IA5String       = "\x16"
+kASN1UniversalTag_UTCTime         = "\x17"
+kASN1UniversalTag_GeneralizedTime = "\x18"
+kASN1UniversalTag_GraphicString   = "\x19"
+kASN1UniversalTag_VisibleString   = "\x1A"
+kASN1UniversalTag_GeneralString   = "\x1B"
+kASN1UniversalTag_UniversalString = "\x1C"
+
+kASN1UniversalTag_Sequence_Constructed = "\x30"
+kASN1UniversalTag_Set_Constructed = "\x31"

src/credentials/tests/BUILD.gn

@@ -81,4 +81,8 @@ if (enable_fuzz_test_targets) {
     sources = [ "FuzzChipCert.cpp" ]
     public_deps = [ "${chip_root}/src/credentials" ]
   }
+  chip_fuzz_target("fuzz-der-cert") {
+    sources = [ "FuzzDERCert.cpp" ]
+    public_deps = [ "${chip_root}/src/credentials" ]
+  }
 }

src/credentials/tests/FuzzDERCert.cpp

@@ -0,0 +1,25 @@
+#include <cstddef>
+#include <cstdint>
+
+#include "credentials/CHIPCert.h"
+
+using namespace chip;
+using namespace chip::Credentials;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t * data, size_t len)
+{
+    ByteSpan span(data, len);
+
+    {
+        ChipDN dn;
+        (void) ExtractSubjectDNFromX509Cert(span, dn);
+    }
+
+    {
+        uint8_t outCertBuf[kMaxCHIPCertLength];
+        MutableByteSpan outCert(outCertBuf);
+        (void) ConvertX509CertToChipCert(span, outCert);
+    }
+
+    return 0;
+}