Bluetooth: Properly check L2CAP config option output buffer lengthsubmit/tizen_4.0/20170915.051857submit/tizen_4.0/20170915.014357submit/tizen/20170915.052049submit/tizen/20170915.014726accepted/tizen/unified/20170915.195818accepted/tizen/4.0/unified/20170915.201910accepted/tizen_unified

commit e860d2c904d1a9f38a24eb44c9f34b8f915a6ea3 upstream.

Validate the output buffer length for L2CAP config requests and responses
to avoid overflowing the stack buffer used for building the option blocks.

Signed-off-by: Ben Seri <ben@armis.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[dh79.pyun: Cherry-pick from mainline to fix CVE-2017-1000251]
Signed-off-by: DoHyun Pyun <dh79.pyun@samsung.com>

Change-Id: I3de2bb146a60c20a90cfcdf10614f3febed3ed8b

1 files changed, 43 insertions, 37 deletions

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 47aa0fe331f..2be79a0e71c 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -79,7 +79,7 @@ static struct sk_buff *l2cap_build_cmd(struct l2cap_conn *conn,
 				       u8 code, u8 ident, u16 dlen, void *data);
 static void l2cap_send_cmd(struct l2cap_conn *conn, u8 ident, u8 code, u16 len,
 			   void *data);
-static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data);
+static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data, size_t data_size);
 static void l2cap_send_disconn_req(struct l2cap_chan *chan, int err);
 
 static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
@@ -1477,7 +1477,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
 
 			set_bit(CONF_REQ_SENT, &chan->conf_state);
 			l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
-				       l2cap_build_conf_req(chan, buf), buf);
+				       l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
 			chan->num_conf_req++;
 		}
 
@@ -2995,12 +2995,15 @@ static inline int l2cap_get_conf_opt(void **ptr, int *type, int *olen,
 	return len;
 }
 
-static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val)
+static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val, size_t size)
 {
 	struct l2cap_conf_opt *opt = *ptr;
 
 	BT_DBG("type 0x%2.2x len %u val 0x%lx", type, len, val);
 
+	if (size < L2CAP_CONF_OPT_SIZE + len)
+		return;
+
 	opt->type = type;
 	opt->len  = len;
 
@@ -3025,7 +3028,7 @@ static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val)
 	*ptr += L2CAP_CONF_OPT_SIZE + len;
 }
 
-static void l2cap_add_opt_efs(void **ptr, struct l2cap_chan *chan)
+static void l2cap_add_opt_efs(void **ptr, struct l2cap_chan *chan, size_t size)
 {
 	struct l2cap_conf_efs efs;
 
@@ -3053,7 +3056,7 @@ static void l2cap_add_opt_efs(void **ptr, struct l2cap_chan *chan)
 	}
 
 	l2cap_add_conf_opt(ptr, L2CAP_CONF_EFS, sizeof(efs),
-			   (unsigned long) &efs);
+			   (unsigned long) &efs, size);
 }
 
 static void l2cap_ack_timeout(struct work_struct *work)
@@ -3199,11 +3202,12 @@ static inline void l2cap_txwin_setup(struct l2cap_chan *chan)
 	chan->ack_win = chan->tx_win;
 }
 
-static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data)
+static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data, size_t data_size)
 {
 	struct l2cap_conf_req *req = data;
 	struct l2cap_conf_rfc rfc = { .mode = chan->mode };
 	void *ptr = req->data;
+	void *endptr = data + data_size;
 	u16 size;
 
 	BT_DBG("chan %p", chan);
@@ -3228,7 +3232,7 @@ static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data)
 
 done:
 	if (chan->imtu != L2CAP_DEFAULT_MTU)
-		l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu);
+		l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu, endptr - ptr);
 
 	switch (chan->mode) {
 	case L2CAP_MODE_BASIC:
@@ -3247,7 +3251,7 @@ done:
 		rfc.max_pdu_size    = 0;
 
 		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-				   (unsigned long) &rfc);
+				   (unsigned long) &rfc, endptr - ptr);
 		break;
 
 	case L2CAP_MODE_ERTM:
@@ -3267,21 +3271,21 @@ done:
 				       L2CAP_DEFAULT_TX_WINDOW);
 
 		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-				   (unsigned long) &rfc);
+				   (unsigned long) &rfc, endptr - ptr);
 
 		if (test_bit(FLAG_EFS_ENABLE, &chan->flags))
-			l2cap_add_opt_efs(&ptr, chan);
+			l2cap_add_opt_efs(&ptr, chan, endptr - ptr);
 
 		if (test_bit(FLAG_EXT_CTRL, &chan->flags))
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2,
-					   chan->tx_win);
+					   chan->tx_win, endptr - ptr);
 
 		if (chan->conn->feat_mask & L2CAP_FEAT_FCS)
 			if (chan->fcs == L2CAP_FCS_NONE ||
 			    test_bit(CONF_RECV_NO_FCS, &chan->conf_state)) {
 				chan->fcs = L2CAP_FCS_NONE;
 				l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1,
-						   chan->fcs);
+						   chan->fcs, endptr - ptr);
 			}
 		break;
 
@@ -3299,17 +3303,17 @@ done:
 		rfc.max_pdu_size = cpu_to_le16(size);
 
 		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-				   (unsigned long) &rfc);
+				   (unsigned long) &rfc, endptr - ptr);
 
 		if (test_bit(FLAG_EFS_ENABLE, &chan->flags))
-			l2cap_add_opt_efs(&ptr, chan);
+			l2cap_add_opt_efs(&ptr, chan, endptr - ptr);
 
 		if (chan->conn->feat_mask & L2CAP_FEAT_FCS)
 			if (chan->fcs == L2CAP_FCS_NONE ||
 			    test_bit(CONF_RECV_NO_FCS, &chan->conf_state)) {
 				chan->fcs = L2CAP_FCS_NONE;
 				l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1,
-						   chan->fcs);
+						   chan->fcs, endptr - ptr);
 			}
 		break;
 	}
@@ -3320,10 +3324,11 @@ done:
 	return ptr - data;
 }
 
-static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data)
+static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data_size)
 {
 	struct l2cap_conf_rsp *rsp = data;
 	void *ptr = rsp->data;
+	void *endptr = data + data_size;
 	void *req = chan->conf_req;
 	int len = chan->conf_len;
 	int type, hint, olen;
@@ -3425,7 +3430,7 @@ done:
 			return -ECONNREFUSED;
 
 		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-				   (unsigned long) &rfc);
+				   (unsigned long) &rfc, endptr - ptr);
 	}
 
 	if (result == L2CAP_CONF_SUCCESS) {
@@ -3438,7 +3443,7 @@ done:
 			chan->omtu = mtu;
 			set_bit(CONF_MTU_DONE, &chan->conf_state);
 		}
-		l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->omtu);
+		l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->omtu, endptr - ptr);
 
 		if (remote_efs) {
 			if (chan->local_stype != L2CAP_SERV_NOTRAFIC &&
@@ -3452,7 +3457,7 @@ done:
 
 				l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS,
 						   sizeof(efs),
-						   (unsigned long) &efs);
+						   (unsigned long) &efs, endptr - ptr);
 			} else {
 				/* Send PENDING Conf Rsp */
 				result = L2CAP_CONF_PENDING;
@@ -3485,7 +3490,7 @@ done:
 			set_bit(CONF_MODE_DONE, &chan->conf_state);
 
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
-					   sizeof(rfc), (unsigned long) &rfc);
+					   sizeof(rfc), (unsigned long) &rfc, endptr - ptr);
 
 			if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) {
 				chan->remote_id = efs.id;
@@ -3499,7 +3504,7 @@ done:
 					le32_to_cpu(efs.sdu_itime);
 				l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS,
 						   sizeof(efs),
-						   (unsigned long) &efs);
+						   (unsigned long) &efs, endptr - ptr);
 			}
 			break;
 
@@ -3513,7 +3518,7 @@ done:
 			set_bit(CONF_MODE_DONE, &chan->conf_state);
 
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-					   (unsigned long) &rfc);
+					   (unsigned long) &rfc, endptr - ptr);
 
 			break;
 
@@ -3535,10 +3540,11 @@ done:
 }
 
 static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
-				void *data, u16 *result)
+				void *data, size_t size, u16 *result)
 {
 	struct l2cap_conf_req *req = data;
 	void *ptr = req->data;
+	void *endptr = data + size;
 	int type, olen;
 	unsigned long val;
 	struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };
@@ -3556,13 +3562,13 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
 				chan->imtu = L2CAP_DEFAULT_MIN_MTU;
 			} else
 				chan->imtu = val;
-			l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu);
+			l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu, endptr - ptr);
 			break;
 
 		case L2CAP_CONF_FLUSH_TO:
 			chan->flush_to = val;
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_FLUSH_TO,
-					   2, chan->flush_to);
+					   2, chan->flush_to, endptr - ptr);
 			break;
 
 		case L2CAP_CONF_RFC:
@@ -3576,13 +3582,13 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
 			chan->fcs = 0;
 
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
-					   sizeof(rfc), (unsigned long) &rfc);
+					   sizeof(rfc), (unsigned long) &rfc, endptr - ptr);
 			break;
 
 		case L2CAP_CONF_EWS:
 			chan->ack_win = min_t(u16, val, chan->ack_win);
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2,
-					   chan->tx_win);
+					   chan->tx_win, endptr - ptr);
 			break;
 
 		case L2CAP_CONF_EFS:
@@ -3595,7 +3601,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
 				return -ECONNREFUSED;
 
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs),
-					   (unsigned long) &efs);
+					   (unsigned long) &efs, endptr - ptr);
 			break;
 
 		case L2CAP_CONF_FCS:
@@ -3714,7 +3720,7 @@ void __l2cap_connect_rsp_defer(struct l2cap_chan *chan)
 	/* END SLP_Bluetooth */
 
 	l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
-		       l2cap_build_conf_req(chan, buf), buf);
+		       l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
 	chan->num_conf_req++;
 }
 
@@ -3922,7 +3928,7 @@ sendresp:
 		u8 buf[128];
 		set_bit(CONF_REQ_SENT, &chan->conf_state);
 		l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
-			       l2cap_build_conf_req(chan, buf), buf);
+			       l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
 		chan->num_conf_req++;
 	}
 
@@ -4014,7 +4020,7 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 		/* END SLP_Bluetooth */
 
 		l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
-			       l2cap_build_conf_req(chan, req), req);
+			       l2cap_build_conf_req(chan, req, sizeof(req)), req);
 		chan->num_conf_req++;
 		break;
 
@@ -4126,7 +4132,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
 	}
 
 	/* Complete config. */
-	len = l2cap_parse_conf_req(chan, rsp);
+	len = l2cap_parse_conf_req(chan, rsp, sizeof(rsp));
 	if (len < 0) {
 		l2cap_send_disconn_req(chan, ECONNRESET);
 		goto unlock;
@@ -4160,7 +4166,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
 	if (!test_and_set_bit(CONF_REQ_SENT, &chan->conf_state)) {
 		u8 buf[64];
 		l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
-			       l2cap_build_conf_req(chan, buf), buf);
+			       l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
 		chan->num_conf_req++;
 	}
 
@@ -4220,7 +4226,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
 			char buf[64];
 
 			len = l2cap_parse_conf_rsp(chan, rsp->data, len,
-						   buf, &result);
+						   buf, sizeof(buf), &result);
 			if (len < 0) {
 				l2cap_send_disconn_req(chan, ECONNRESET);
 				goto done;
@@ -4250,7 +4256,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
 			/* throw out any old stored conf requests */
 			result = L2CAP_CONF_SUCCESS;
 			len = l2cap_parse_conf_rsp(chan, rsp->data, len,
-						   req, &result);
+						   req, sizeof(req), &result);
 			if (len < 0) {
 				l2cap_send_disconn_req(chan, ECONNRESET);
 				goto done;
@@ -4844,7 +4850,7 @@ static void l2cap_do_create(struct l2cap_chan *chan, int result,
 			set_bit(CONF_REQ_SENT, &chan->conf_state);
 			l2cap_send_cmd(chan->conn, l2cap_get_ident(chan->conn),
 				       L2CAP_CONF_REQ,
-				       l2cap_build_conf_req(chan, buf), buf);
+				       l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
 			chan->num_conf_req++;
 		}
 	}
@@ -7487,7 +7493,7 @@ int l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt)
 				set_bit(CONF_REQ_SENT, &chan->conf_state);
 				l2cap_send_cmd(conn, l2cap_get_ident(conn),
 					       L2CAP_CONF_REQ,
-					       l2cap_build_conf_req(chan, buf),
+					       l2cap_build_conf_req(chan, buf, sizeof(buf)),
 					       buf);
 				chan->num_conf_req++;
 			}