Add PEM fuzzer

This fuzzer can find CVE-2022-4450

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20242)

2 files changed, 69 insertions, 2 deletions

diff --git a/fuzz/build.info b/fuzz/build.info
index bdeb075fdd..af5f550f00 100644
--- a/fuzz/build.info
+++ b/fuzz/build.info
@@ -10,7 +10,7 @@
 
 IF[{- !$disabled{"fuzz-afl"} || !$disabled{"fuzz-libfuzzer"} -}]
   PROGRAMS{noinst}=asn1 asn1parse bignum bndiv client conf crl server smime x509
-  PROGRAMS{noinst}=punycode
+  PROGRAMS{noinst}=punycode pem
   PROGRAMS{noinst}=v3name
 
   IF[{- !$disabled{"cmp"} -}]
@@ -65,6 +65,10 @@ IF[{- !$disabled{"fuzz-afl"} || !$disabled{"fuzz-libfuzzer"} -}]
   INCLUDE[ct]=../include {- $ex_inc -}
   DEPEND[ct]=../libcrypto {- $ex_lib -}
 
+  SOURCE[pem]=pem.c driver.c
+  INCLUDE[pem]=../include {- $ex_inc -}
+  DEPEND[pem]=../libcrypto.a {- $ex_lib -}
+
   SOURCE[punycode]=punycode.c driver.c
   INCLUDE[punycode]=../include {- $ex_inc -}
   DEPEND[punycode]=../libcrypto.a {- $ex_lib -}
@@ -88,7 +92,7 @@ ENDIF
 
 IF[{- !$disabled{tests} -}]
   PROGRAMS{noinst}=asn1-test asn1parse-test bignum-test bndiv-test client-test conf-test crl-test server-test smime-test x509-test
-  PROGRAMS{noinst}=punycode-test
+  PROGRAMS{noinst}=punycode-test pem-test
   PROGRAMS{noinst}=v3name-test
 
   IF[{- !$disabled{"cmp"} -}]
@@ -144,6 +148,10 @@ IF[{- !$disabled{tests} -}]
   INCLUDE[ct-test]=../include
   DEPEND[ct-test]=../libcrypto
 
+  SOURCE[pem-test]=pem.c test-corpus.c
+  INCLUDE[pem-test]=../include
+  DEPEND[pem-test]=../libcrypto.a
+
   SOURCE[punycode-test]=punycode.c test-corpus.c
   INCLUDE[punycode-test]=../include
   DEPEND[punycode-test]=../libcrypto.a
diff --git a/fuzz/pem.c b/fuzz/pem.c
new file mode 100644
index 0000000000..4b2cf701e7
--- /dev/null
+++ b/fuzz/pem.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * https://www.openssl.org/source/license.html
+ * or in the file LICENSE in the source distribution.
+ */
+
+#include <openssl/pem.h>
+#include <openssl/err.h>
+#include "fuzzer.h"
+
+int FuzzerInitialize(int *argc, char ***argv)
+{
+    OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL);
+    ERR_clear_error();
+    CRYPTO_free_ex_index(0, -1);
+    return 1;
+}
+
+int FuzzerTestOneInput(const uint8_t *buf, size_t len)
+{
+    BIO *in;
+    char *name = NULL, *header = NULL;
+    unsigned char *data = NULL;
+    long outlen;
+
+    if (len <= 1)
+        return 0;
+
+    in = BIO_new(BIO_s_mem());
+    OPENSSL_assert((size_t)BIO_write(in, buf + 1, len - 1) == len - 1);
+    if (PEM_read_bio_ex(in, &name, &header, &data, &outlen, buf[0]) == 1) {
+	/* Try to read all the data we get to see if allocated properly. */
+        BIO_write(in, name, strlen(name));
+	BIO_write(in, header, strlen(header));
+	BIO_write(in, data, outlen);
+    }
+    if (buf[0] & PEM_FLAG_SECURE) {
+        OPENSSL_secure_free(name);
+        OPENSSL_secure_free(header);
+        OPENSSL_secure_free(data);
+    } else {
+        OPENSSL_free(name);
+        OPENSSL_free(header);
+        OPENSSL_free(data);
+    }
+
+    BIO_free(in);
+    ERR_clear_error();
+
+    return 0;
+}
+
+void FuzzerCleanup(void)
+{
+}