Add initial fuzzers to be used by oss-fuzz.

These are not yet hooked up to the sudo build.

lib/iolog/regress/fuzz/fuzz_iolog_json.c

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2021 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#if defined(HAVE_STDINT_H)
+# include <stdint.h>
+#elif defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#endif
+
+#include "sudo_compat.h"
+#include "sudo_debug.h"
+#include "sudo_eventlog.h"
+#include "sudo_iolog.h"
+#include "sudo_util.h"
+
+#include "iolog_json.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+    struct eventlog *evlog = NULL;
+    FILE *fp;
+
+    /* Operate in-memory, do not fclose or it will free() data. */
+    fp = fmemopen((void *)data, size, "r");
+    if (fp == NULL)
+        return 0;
+
+    /* Parsed contents of an log.json file are stored in evlog. */
+    if ((evlog = calloc(1, sizeof(*evlog))) == NULL)
+	return 0;
+    evlog->runuid = (uid_t)-1;
+    evlog->rungid = (gid_t)-1;
+
+    /* Try to parse buffer as a JSON-format I/O log info file. */
+    iolog_parse_loginfo_json(fp, "fuzz.json", evlog);
+    eventlog_free(evlog);
+
+    return 0;
+}