DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C495121470
Date:   Tue, 16 Oct 2018 23:22:42 +0300
From:   Matias Karhumaa <matias.karhumaa@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [PATCH 07/12] btmon: fix segfault caused by integer underflow
Message-ID: <20181016202242.GA85013@Matias-MacBook-Air.local>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.6.1 (2016-04-27)
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Fix segfault caused by integer underflow in set_event_filter_cmd().
Fix is to check that size is big enough before subtracting to prevent
underflow.

Crash was found by fuzzing btmon with AFL.
---
 monitor/packet.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/monitor/packet.c b/monitor/packet.c
index abdc18aa2..461f5e84b 100644
--- a/monitor/packet.c
+++ b/monitor/packet.c
@@ -4726,6 +4726,10 @@ static void set_event_filter_cmd(const void *data, uint8_t size)
 		break;
 
 	case 0x01:
+		if (size < 2) {
+			print_text(COLOR_ERROR, "  invalid parameter size");
+			break;
+		}
 		filter = *((const uint8_t *) (data + 1));
 
 		switch (filter) {
@@ -4765,11 +4769,21 @@ static void set_event_filter_cmd(const void *data, uint8_t size)
 			break;
 		}
 
+		if (size < 2) {
+                        print_text(COLOR_ERROR, "  invalid parameter size");
+                        break;
+                }
+
 		print_field("Filter: %s (0x%2.2x)", str, filter);
 		packet_hexdump(data + 2, size - 2);
 		break;
 
 	default:
+		if (size < 2) {
+                        print_text(COLOR_ERROR, "  invalid parameter size");
+                        break;
+                }
+
 		filter = *((const uint8_t *) (data + 1));
 
 		print_field("Filter: Reserved (0x%2.2x)", filter);
-- 
2.17.1