Add simple fuzzer for sudo.conf parser.

lib/util/regress/fuzz/fuzz_sudo_conf.c

@@ -0,0 +1,59 @@
+/*
+ * 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_conf.h"
+#include "sudo_debug.h"
+#include "sudo_util.h"
+
+int
+LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+    char tempfile[] = "/tmp/sudo_conf.XXXXXX";
+    size_t nwritten;
+    int fd;
+
+    /* sudo_conf_read() uses a conf file path, not an open file. */
+    fd = mkstemp(tempfile);
+    if (fd == -1)
+	return 0;
+    nwritten = write(fd, data, size);
+    if (nwritten != size) {
+	close(fd);
+	return 0;
+    }
+    close(fd);
+
+    /* sudo_conf_read() will re-init and free old data each time it runs. */
+    sudo_conf_clear_paths();
+    sudo_conf_read(tempfile, SUDO_CONF_ALL);
+
+    unlink(tempfile);
+
+    return 0;
+}