fuzz: add nmblib/parse_packet target

We want to ensure that parse_packet() can parse a packet without
crashing, and that that parsed packet won't cause trouble further down
the line.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

Autobuild-User(master): Gary Lockyer <gary@samba.org>
Autobuild-Date(master): Wed Jan 15 21:24:31 UTC 2020 on sn-devel-184

1 files changed, 56 insertions, 0 deletions

diff --git a/lib/fuzzing/fuzz_nmblib_parse_packet.c b/lib/fuzzing/fuzz_nmblib_parse_packet.c
new file mode 100644
index 00000000000..7b35abe9f97
--- /dev/null
+++ b/lib/fuzzing/fuzz_nmblib_parse_packet.c
@@ -0,0 +1,56 @@
+/*
+  Fuzz NMB parse_packet
+  Copyright (C) Catalyst IT 2020
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "../../source3/include/includes.h"
+#include "libsmb/libsmb.h"
+#include "libsmb/nmblib.h"
+#include "fuzzing/fuzzing.h"
+
+#define PORT 138
+#define MAX_LENGTH (1024 * 1024)
+char buf[MAX_LENGTH + 1];
+
+
+int LLVMFuzzerTestOneInput(uint8_t *input, size_t len)
+{
+	struct packet_struct *p = NULL;
+	struct in_addr ip = {
+		0x0100007f /* 127.0.0.1 */
+	};
+
+	p = parse_packet((char *)input,
+			 len,
+			 NMB_PACKET,
+			 ip,
+			 PORT);
+	/*
+	 * We expect NULL (parse failure) most of the time.
+	 *
+	 * When it is not NULL we want to ensure the parsed packet is
+	 * reasonably sound.
+	 */
+
+	if (p != NULL) {
+		struct nmb_packet *nmb = &p->packet.nmb;
+		pull_ascii_nstring(buf, MAX_LENGTH,
+				   nmb->question.question_name.name);
+		build_packet(buf, MAX_LENGTH, p);
+		free_packet(p);
+	}
+	return 0;
+}