commit f4777569204cb59f2f04fbe9ef4e9a6918209104
author Marcel Holtmann <marcel@holtmann.org> Mon Jan 08 02:16:23 2007 +0100
committer David S. Miller <davem@sunset.davemloft.net> Tue Jan 09 00:29:53 2007 -0800
tree c42ce096df9584d4c83b7003c7bbbd8c30be970d
parent d2e7543c41755f4ec75385536b109d5f084fe734

[Bluetooth] Add packet size checks for CAPI messages

With malformed packets it might be possible to overwrite internal
CMTP and CAPI data structures. This patch adds additional length
checks to prevent these kinds of remote attacks.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/cmtp/capi.c

diff --git a/net/bluetooth/cmtp/capi.c b/net/bluetooth/cmtp/capi.c
index be04e9f..ab166b4 100644
--- a/net/bluetooth/cmtp/capi.c
+++ b/net/bluetooth/cmtp/capi.c
@@ -196,6 +196,9 @@
 
 	switch (CAPIMSG_SUBCOMMAND(skb->data)) {
 	case CAPI_CONF:
+		if (skb->len < CAPI_MSG_BASELEN + 10)
+			break;
+
 		func = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 5);
 		info = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 8);
 
@@ -226,6 +229,9 @@
 			break;
 
 		case CAPI_FUNCTION_GET_PROFILE:
+			if (skb->len < CAPI_MSG_BASELEN + 11 + sizeof(capi_profile))
+				break;
+
 			controller = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 11);
 			msgnum = CAPIMSG_MSGID(skb->data);
 
@@ -246,17 +252,26 @@
 			break;
 
 		case CAPI_FUNCTION_GET_MANUFACTURER:
+			if (skb->len < CAPI_MSG_BASELEN + 15)
+				break;
+
 			controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 10);
 
 			if (!info && ctrl) {
+				int len = min_t(uint, CAPI_MANUFACTURER_LEN,
+						skb->data[CAPI_MSG_BASELEN + 14]);
+
+				memset(ctrl->manu, 0, CAPI_MANUFACTURER_LEN);
 				strncpy(ctrl->manu,
-					skb->data + CAPI_MSG_BASELEN + 15,
-					skb->data[CAPI_MSG_BASELEN + 14]);
+					skb->data + CAPI_MSG_BASELEN + 15, len);
 			}
 
 			break;
 
 		case CAPI_FUNCTION_GET_VERSION:
+			if (skb->len < CAPI_MSG_BASELEN + 32)
+				break;
+
 			controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 12);
 
 			if (!info && ctrl) {
@@ -269,13 +284,18 @@
 			break;
 
 		case CAPI_FUNCTION_GET_SERIAL_NUMBER:
+			if (skb->len < CAPI_MSG_BASELEN + 17)
+				break;
+
 			controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 12);
 
 			if (!info && ctrl) {
+				int len = min_t(uint, CAPI_SERIAL_LEN,
+						skb->data[CAPI_MSG_BASELEN + 16]);
+
 				memset(ctrl->serial, 0, CAPI_SERIAL_LEN);
 				strncpy(ctrl->serial,
-					skb->data + CAPI_MSG_BASELEN + 17,
-					skb->data[CAPI_MSG_BASELEN + 16]);
+					skb->data + CAPI_MSG_BASELEN + 17, len);
 			}
 
 			break;
@@ -284,14 +304,18 @@
 		break;
 
 	case CAPI_IND:
+		if (skb->len < CAPI_MSG_BASELEN + 6)
+			break;
+
 		func = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 3);
 
 		if (func == CAPI_FUNCTION_LOOPBACK) {
+			int len = min_t(uint, skb->len - CAPI_MSG_BASELEN - 6,
+						skb->data[CAPI_MSG_BASELEN + 5]);
 			appl = CAPIMSG_APPID(skb->data);
 			msgnum = CAPIMSG_MSGID(skb->data);
 			cmtp_send_interopmsg(session, CAPI_RESP, appl, msgnum, func,
-						skb->data + CAPI_MSG_BASELEN + 6,
-						skb->data[CAPI_MSG_BASELEN + 5]);
+						skb->data + CAPI_MSG_BASELEN + 6, len);
 		}
 
 		break;
@@ -309,6 +333,9 @@
 
 	BT_DBG("session %p skb %p len %d", session, skb, skb->len);
 
+	if (skb->len < CAPI_MSG_BASELEN)
+		return;
+
 	if (CAPIMSG_COMMAND(skb->data) == CAPI_INTEROPERABILITY) {
 		cmtp_recv_interopmsg(session, skb);
 		return;