Bluetooth: Prevent buffer overflow in l2cap config request, CVE-2011-2497
[linux-flexiantxendom0-natty.git] / net / bluetooth / l2cap.c
index 449cbdd..04120ff 100644 (file)
@@ -1,6 +1,8 @@
 /*
    BlueZ - Bluetooth protocol stack for Linux
    Copyright (C) 2000-2001 Qualcomm Incorporated
+   Copyright (C) 2009-2010 Gustavo F. Padovan <gustavo@padovan.org>
+   Copyright (C) 2010 Google Inc.
 
    Written 2000,2001 by Maxim Krasnyansky <maxk@qualcomm.com>
 
@@ -53,9 +55,9 @@
 #include <net/bluetooth/hci_core.h>
 #include <net/bluetooth/l2cap.h>
 
-#define VERSION "2.14"
+#define VERSION "2.15"
 
-static int enable_ertm = 0;
+static int disable_ertm;
 
 static u32 l2cap_feat_mask = L2CAP_FEAT_FIXED_CHAN;
 static u8 l2cap_fixed_chan[8] = { 0x02, };
@@ -81,6 +83,18 @@ static struct sk_buff *l2cap_build_cmd(struct l2cap_conn *conn,
 static int l2cap_ertm_data_rcv(struct sock *sk, struct sk_buff *skb);
 
 /* ---- L2CAP timers ---- */
+static void l2cap_sock_set_timer(struct sock *sk, long timeout)
+{
+       BT_DBG("sk %p state %d timeout %ld", sk, sk->sk_state, timeout);
+       sk_reset_timer(sk, &sk->sk_timer, jiffies + timeout);
+}
+
+static void l2cap_sock_clear_timer(struct sock *sk)
+{
+       BT_DBG("sock %p state %d", sk, sk->sk_state);
+       sk_stop_timer(sk, &sk->sk_timer);
+}
+
 static void l2cap_sock_timeout(unsigned long arg)
 {
        struct sock *sk = (struct sock *) arg;
@@ -90,6 +104,14 @@ static void l2cap_sock_timeout(unsigned long arg)
 
        bh_lock_sock(sk);
 
+       if (sock_owned_by_user(sk)) {
+               /* sk is owned by user. Try again later */
+               l2cap_sock_set_timer(sk, HZ / 5);
+               bh_unlock_sock(sk);
+               sock_put(sk);
+               return;
+       }
+
        if (sk->sk_state == BT_CONNECTED || sk->sk_state == BT_CONFIG)
                reason = ECONNREFUSED;
        else if (sk->sk_state == BT_CONNECT &&
@@ -106,18 +128,6 @@ static void l2cap_sock_timeout(unsigned long arg)
        sock_put(sk);
 }
 
-static void l2cap_sock_set_timer(struct sock *sk, long timeout)
-{
-       BT_DBG("sk %p state %d timeout %ld", sk, sk->sk_state, timeout);
-       sk_reset_timer(sk, &sk->sk_timer, jiffies + timeout);
-}
-
-static void l2cap_sock_clear_timer(struct sock *sk)
-{
-       BT_DBG("sock %p state %d", sk, sk->sk_state);
-       sk_stop_timer(sk, &sk->sk_timer);
-}
-
 /* ---- L2CAP channels ---- */
 static struct sock *__l2cap_get_chan_by_dcid(struct l2cap_chan_list *l, u16 cid)
 {
@@ -295,33 +305,44 @@ static void l2cap_chan_del(struct sock *sk, int err)
        }
 }
 
-/* Service level security */
-static inline int l2cap_check_security(struct sock *sk)
+static inline u8 l2cap_get_auth_type(struct sock *sk)
 {
-       struct l2cap_conn *conn = l2cap_pi(sk)->conn;
-       __u8 auth_type;
+       if (sk->sk_type == SOCK_RAW) {
+               switch (l2cap_pi(sk)->sec_level) {
+               case BT_SECURITY_HIGH:
+                       return HCI_AT_DEDICATED_BONDING_MITM;
+               case BT_SECURITY_MEDIUM:
+                       return HCI_AT_DEDICATED_BONDING;
+               default:
+                       return HCI_AT_NO_BONDING;
+               }
+       } else if (l2cap_pi(sk)->psm == cpu_to_le16(0x0001)) {
+               if (l2cap_pi(sk)->sec_level == BT_SECURITY_LOW)
+                       l2cap_pi(sk)->sec_level = BT_SECURITY_SDP;
 
-       if (l2cap_pi(sk)->psm == cpu_to_le16(0x0001)) {
                if (l2cap_pi(sk)->sec_level == BT_SECURITY_HIGH)
-                       auth_type = HCI_AT_NO_BONDING_MITM;
+                       return HCI_AT_NO_BONDING_MITM;
                else
-                       auth_type = HCI_AT_NO_BONDING;
-
-               if (l2cap_pi(sk)->sec_level == BT_SECURITY_LOW)
-                       l2cap_pi(sk)->sec_level = BT_SECURITY_SDP;
+                       return HCI_AT_NO_BONDING;
        } else {
                switch (l2cap_pi(sk)->sec_level) {
                case BT_SECURITY_HIGH:
-                       auth_type = HCI_AT_GENERAL_BONDING_MITM;
-                       break;
+                       return HCI_AT_GENERAL_BONDING_MITM;
                case BT_SECURITY_MEDIUM:
-                       auth_type = HCI_AT_GENERAL_BONDING;
-                       break;
+                       return HCI_AT_GENERAL_BONDING;
                default:
-                       auth_type = HCI_AT_NO_BONDING;
-                       break;
+                       return HCI_AT_NO_BONDING;
                }
        }
+}
+
+/* Service level security */
+static inline int l2cap_check_security(struct sock *sk)
+{
+       struct l2cap_conn *conn = l2cap_pi(sk)->conn;
+       __u8 auth_type;
+
+       auth_type = l2cap_get_auth_type(sk);
 
        return hci_conn_security(conn->hcon, l2cap_pi(sk)->sec_level,
                                                                auth_type);
@@ -462,7 +483,7 @@ static void l2cap_do_start(struct sock *sk)
 static inline int l2cap_mode_supported(__u8 mode, __u32 feat_mask)
 {
        u32 local_feat_mask = l2cap_feat_mask;
-       if (enable_ertm)
+       if (!disable_ertm)
                local_feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING;
 
        switch (mode) {
@@ -741,11 +762,13 @@ found:
 /* Find socket with psm and source bdaddr.
  * Returns closest match.
  */
-static struct sock *__l2cap_get_sock_by_psm(int state, __le16 psm, bdaddr_t *src)
+static struct sock *l2cap_get_sock_by_psm(int state, __le16 psm, bdaddr_t *src)
 {
        struct sock *sk = NULL, *sk1 = NULL;
        struct hlist_node *node;
 
+       read_lock(&l2cap_sk_list.lock);
+
        sk_for_each(sk, node, &l2cap_sk_list.head) {
                if (state && sk->sk_state != state)
                        continue;
@@ -760,20 +783,10 @@ static struct sock *__l2cap_get_sock_by_psm(int state, __le16 psm, bdaddr_t *src
                                sk1 = sk;
                }
        }
-       return node ? sk : sk1;
-}
 
-/* Find socket with given address (psm, src).
- * Returns locked socket */
-static inline struct sock *l2cap_get_sock_by_psm(int state, __le16 psm, bdaddr_t *src)
-{
-       struct sock *s;
-       read_lock(&l2cap_sk_list.lock);
-       s = __l2cap_get_sock_by_psm(state, psm, src);
-       if (s)
-               bh_lock_sock(s);
        read_unlock(&l2cap_sk_list.lock);
-       return s;
+
+       return node ? sk : sk1;
 }
 
 static void l2cap_sock_destruct(struct sock *sk)
@@ -846,6 +859,7 @@ static void __l2cap_sock_close(struct sock *sk, int reason)
                                result = L2CAP_CR_SEC_BLOCK;
                        else
                                result = L2CAP_CR_BAD_PSM;
+                       sk->sk_state = BT_DISCONN;
 
                        rsp.scid   = cpu_to_le16(l2cap_pi(sk)->dcid);
                        rsp.dcid   = cpu_to_le16(l2cap_pi(sk)->scid);
@@ -901,7 +915,7 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
        } else {
                pi->imtu = L2CAP_DEFAULT_MTU;
                pi->omtu = 0;
-               if (enable_ertm && sk->sk_type == SOCK_STREAM) {
+               if (!disable_ertm && sk->sk_type == SOCK_STREAM) {
                        pi->mode = L2CAP_MODE_ERTM;
                        pi->conf_state |= L2CAP_CONF_STATE2_DEVICE;
                } else {
@@ -1006,10 +1020,20 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
                goto done;
        }
 
-       if (la.l2_psm && __le16_to_cpu(la.l2_psm) < 0x1001 &&
-                               !capable(CAP_NET_BIND_SERVICE)) {
-               err = -EACCES;
-               goto done;
+       if (la.l2_psm) {
+               __u16 psm = __le16_to_cpu(la.l2_psm);
+
+               /* PSM must be odd and lsb of upper byte must be 0 */
+               if ((psm & 0x0101) != 0x0001) {
+                       err = -EINVAL;
+                       goto done;
+               }
+
+               /* Restrict usage of well-known PSMs */
+               if (psm < 0x1001 && !capable(CAP_NET_BIND_SERVICE)) {
+                       err = -EACCES;
+                       goto done;
+               }
        }
 
        write_lock_bh(&l2cap_sk_list.lock);
@@ -1056,39 +1080,7 @@ static int l2cap_do_connect(struct sock *sk)
 
        err = -ENOMEM;
 
-       if (sk->sk_type == SOCK_RAW) {
-               switch (l2cap_pi(sk)->sec_level) {
-               case BT_SECURITY_HIGH:
-                       auth_type = HCI_AT_DEDICATED_BONDING_MITM;
-                       break;
-               case BT_SECURITY_MEDIUM:
-                       auth_type = HCI_AT_DEDICATED_BONDING;
-                       break;
-               default:
-                       auth_type = HCI_AT_NO_BONDING;
-                       break;
-               }
-       } else if (l2cap_pi(sk)->psm == cpu_to_le16(0x0001)) {
-               if (l2cap_pi(sk)->sec_level == BT_SECURITY_HIGH)
-                       auth_type = HCI_AT_NO_BONDING_MITM;
-               else
-                       auth_type = HCI_AT_NO_BONDING;
-
-               if (l2cap_pi(sk)->sec_level == BT_SECURITY_LOW)
-                       l2cap_pi(sk)->sec_level = BT_SECURITY_SDP;
-       } else {
-               switch (l2cap_pi(sk)->sec_level) {
-               case BT_SECURITY_HIGH:
-                       auth_type = HCI_AT_GENERAL_BONDING_MITM;
-                       break;
-               case BT_SECURITY_MEDIUM:
-                       auth_type = HCI_AT_GENERAL_BONDING;
-                       break;
-               default:
-                       auth_type = HCI_AT_NO_BONDING;
-                       break;
-               }
-       }
+       auth_type = l2cap_get_auth_type(sk);
 
        hcon = hci_connect(hdev, ACL_LINK, dst,
                                        l2cap_pi(sk)->sec_level, auth_type);
@@ -1115,7 +1107,8 @@ static int l2cap_do_connect(struct sock *sk)
                if (sk->sk_type != SOCK_SEQPACKET &&
                                sk->sk_type != SOCK_STREAM) {
                        l2cap_sock_clear_timer(sk);
-                       sk->sk_state = BT_CONNECTED;
+                       if (l2cap_check_security(sk))
+                               sk->sk_state = BT_CONNECTED;
                } else
                        l2cap_do_start(sk);
        }
@@ -1158,7 +1151,7 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr, int al
                break;
        case L2CAP_MODE_ERTM:
        case L2CAP_MODE_STREAMING:
-               if (enable_ertm)
+               if (!disable_ertm)
                        break;
                /* fall through */
        default:
@@ -1188,6 +1181,13 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr, int al
                goto done;
        }
 
+       /* PSM must be odd and lsb of upper byte must be 0 */
+       if ((__le16_to_cpu(la.l2_psm) & 0x0101) != 0x0001 &&
+               sk->sk_type != SOCK_RAW) {
+               err = -EINVAL;
+               goto done;
+       }
+
        /* Set destination address and psm */
        bacpy(&bt_sk(sk)->dst, &la.l2_bdaddr);
        l2cap_pi(sk)->psm = la.l2_psm;
@@ -1224,7 +1224,7 @@ static int l2cap_sock_listen(struct socket *sock, int backlog)
                break;
        case L2CAP_MODE_ERTM:
        case L2CAP_MODE_STREAMING:
-               if (enable_ertm)
+               if (!disable_ertm)
                        break;
                /* fall through */
        default:
@@ -1439,33 +1439,23 @@ static inline void l2cap_do_send(struct sock *sk, struct sk_buff *skb)
 
 static void l2cap_streaming_send(struct sock *sk)
 {
-       struct sk_buff *skb, *tx_skb;
+       struct sk_buff *skb;
        struct l2cap_pinfo *pi = l2cap_pi(sk);
        u16 control, fcs;
 
-       while ((skb = sk->sk_send_head)) {
-               tx_skb = skb_clone(skb, GFP_ATOMIC);
-
-               control = get_unaligned_le16(tx_skb->data + L2CAP_HDR_SIZE);
+       while ((skb = skb_dequeue(TX_QUEUE(sk)))) {
+               control = get_unaligned_le16(skb->data + L2CAP_HDR_SIZE);
                control |= pi->next_tx_seq << L2CAP_CTRL_TXSEQ_SHIFT;
-               put_unaligned_le16(control, tx_skb->data + L2CAP_HDR_SIZE);
+               put_unaligned_le16(control, skb->data + L2CAP_HDR_SIZE);
 
                if (pi->fcs == L2CAP_FCS_CRC16) {
-                       fcs = crc16(0, (u8 *)tx_skb->data, tx_skb->len - 2);
-                       put_unaligned_le16(fcs, tx_skb->data + tx_skb->len - 2);
+                       fcs = crc16(0, (u8 *)skb->data, skb->len - 2);
+                       put_unaligned_le16(fcs, skb->data + skb->len - 2);
                }
 
-               l2cap_do_send(sk, tx_skb);
+               l2cap_do_send(sk, skb);
 
                pi->next_tx_seq = (pi->next_tx_seq + 1) % 64;
-
-               if (skb_queue_is_last(TX_QUEUE(sk), skb))
-                       sk->sk_send_head = NULL;
-               else
-                       sk->sk_send_head = skb_queue_next(TX_QUEUE(sk), skb);
-
-               skb = skb_dequeue(TX_QUEUE(sk));
-               kfree_skb(skb);
        }
 }
 
@@ -1643,7 +1633,7 @@ static inline int l2cap_skbuff_fromiovec(struct sock *sk, struct msghdr *msg, in
 
                *frag = bt_skb_send_alloc(sk, count, msg->msg_flags & MSG_DONTWAIT, &err);
                if (!*frag)
-                       return -EFAULT;
+                       return err;
                if (memcpy_fromiovec(skb_put(*frag, count), msg->msg_iov, count))
                        return -EFAULT;
 
@@ -1669,7 +1659,7 @@ static struct sk_buff *l2cap_create_connless_pdu(struct sock *sk, struct msghdr
        skb = bt_skb_send_alloc(sk, count + hlen,
                        msg->msg_flags & MSG_DONTWAIT, &err);
        if (!skb)
-               return ERR_PTR(-ENOMEM);
+               return ERR_PTR(err);
 
        /* Create L2CAP header */
        lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
@@ -1698,7 +1688,7 @@ static struct sk_buff *l2cap_create_basic_pdu(struct sock *sk, struct msghdr *ms
        skb = bt_skb_send_alloc(sk, count + hlen,
                        msg->msg_flags & MSG_DONTWAIT, &err);
        if (!skb)
-               return ERR_PTR(-ENOMEM);
+               return ERR_PTR(err);
 
        /* Create L2CAP header */
        lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
@@ -1735,7 +1725,7 @@ static struct sk_buff *l2cap_create_iframe_pdu(struct sock *sk, struct msghdr *m
        skb = bt_skb_send_alloc(sk, count + hlen,
                        msg->msg_flags & MSG_DONTWAIT, &err);
        if (!skb)
-               return ERR_PTR(-ENOMEM);
+               return ERR_PTR(err);
 
        /* Create L2CAP header */
        lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
@@ -1884,8 +1874,8 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
                if (pi->mode == L2CAP_MODE_STREAMING) {
                        l2cap_streaming_send(sk);
                } else {
-                       if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY &&
-                                       pi->conn_state && L2CAP_CONN_WAIT_F) {
+                       if ((pi->conn_state & L2CAP_CONN_REMOTE_BUSY) &&
+                                       (pi->conn_state & L2CAP_CONN_WAIT_F)) {
                                err = len;
                                break;
                        }
@@ -1942,6 +1932,9 @@ static int l2cap_sock_recvmsg(struct kiocb *iocb, struct socket *sock, struct ms
 
        release_sock(sk);
 
+       if (sock->type == SOCK_STREAM)
+               return bt_sock_stream_recvmsg(iocb, sock, msg, len, flags);
+
        return bt_sock_recvmsg(iocb, sock, msg, len, flags);
 }
 
@@ -1958,6 +1951,11 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 
        switch (optname) {
        case L2CAP_OPTIONS:
+               if (sk->sk_state == BT_CONNECTED) {
+                       err = -EINVAL;
+                       break;
+               }
+
                opts.imtu     = l2cap_pi(sk)->imtu;
                opts.omtu     = l2cap_pi(sk)->omtu;
                opts.flush_to = l2cap_pi(sk)->flush_to;
@@ -1984,7 +1982,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
                        break;
                case L2CAP_MODE_ERTM:
                case L2CAP_MODE_STREAMING:
-                       if (enable_ertm)
+                       if (!disable_ertm)
                                break;
                        /* fall through */
                default:
@@ -2156,6 +2154,7 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __us
                        break;
                }
 
+               memset(&cinfo, 0, sizeof(cinfo));
                cinfo.hci_handle = l2cap_pi(sk)->conn->hcon->handle;
                memcpy(cinfo.dev_class, l2cap_pi(sk)->conn->hcon->dev_class, 3);
 
@@ -2404,11 +2403,11 @@ static inline int l2cap_get_conf_opt(void **ptr, int *type, int *olen, unsigned
                break;
 
        case 2:
-               *val = __le16_to_cpu(*((__le16 *) opt->val));
+               *val = get_unaligned_le16(opt->val);
                break;
 
        case 4:
-               *val = __le32_to_cpu(*((__le32 *) opt->val));
+               *val = get_unaligned_le32(opt->val);
                break;
 
        default:
@@ -2435,11 +2434,11 @@ static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val)
                break;
 
        case 2:
-               *((__le16 *) opt->val) = cpu_to_le16(val);
+               put_unaligned_le16(val, opt->val);
                break;
 
        case 4:
-               *((__le32 *) opt->val) = cpu_to_le32(val);
+               put_unaligned_le32(val, opt->val);
                break;
 
        default:
@@ -2525,6 +2524,10 @@ done:
                if (pi->imtu != L2CAP_DEFAULT_MTU)
                        l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, pi->imtu);
 
+               if (!(pi->conn->feat_mask & L2CAP_FEAT_ERTM) &&
+                               !(pi->conn->feat_mask & L2CAP_FEAT_STREAMING))
+                       break;
+
                rfc.mode            = L2CAP_MODE_BASIC;
                rfc.txwin_size      = 0;
                rfc.max_transmit    = 0;
@@ -2532,6 +2535,8 @@ done:
                rfc.monitor_timeout = 0;
                rfc.max_pdu_size    = 0;
 
+               l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
+                                                       (unsigned long) &rfc);
                break;
 
        case L2CAP_MODE_ERTM:
@@ -2544,6 +2549,9 @@ done:
                if (L2CAP_DEFAULT_MAX_PDU_SIZE > pi->conn->mtu - 10)
                        rfc.max_pdu_size = cpu_to_le16(pi->conn->mtu - 10);
 
+               l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
+                                                       (unsigned long) &rfc);
+
                if (!(pi->conn->feat_mask & L2CAP_FEAT_FCS))
                        break;
 
@@ -2564,6 +2572,9 @@ done:
                if (L2CAP_DEFAULT_MAX_PDU_SIZE > pi->conn->mtu - 10)
                        rfc.max_pdu_size = cpu_to_le16(pi->conn->mtu - 10);
 
+               l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
+                                                       (unsigned long) &rfc);
+
                if (!(pi->conn->feat_mask & L2CAP_FEAT_FCS))
                        break;
 
@@ -2575,9 +2586,6 @@ done:
                break;
        }
 
-       l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-                                               (unsigned long) &rfc);
-
        /* FIXME: Need actual value of the flush timeout */
        //if (flush_to != L2CAP_DEFAULT_FLUSH_TO)
        //   l2cap_add_conf_opt(&ptr, L2CAP_CONF_FLUSH_TO, 2, pi->flush_to);
@@ -2694,8 +2702,9 @@ done:
                case L2CAP_MODE_ERTM:
                        pi->remote_tx_win = rfc.txwin_size;
                        pi->remote_max_tx = rfc.max_transmit;
-                       if (rfc.max_pdu_size > pi->conn->mtu - 10)
-                               rfc.max_pdu_size = le16_to_cpu(pi->conn->mtu - 10);
+
+                       if (le16_to_cpu(rfc.max_pdu_size) > pi->conn->mtu - 10)
+                               rfc.max_pdu_size = cpu_to_le16(pi->conn->mtu - 10);
 
                        pi->remote_mps = le16_to_cpu(rfc.max_pdu_size);
 
@@ -2712,8 +2721,8 @@ done:
                        break;
 
                case L2CAP_MODE_STREAMING:
-                       if (rfc.max_pdu_size > pi->conn->mtu - 10)
-                               rfc.max_pdu_size = le16_to_cpu(pi->conn->mtu - 10);
+                       if (le16_to_cpu(rfc.max_pdu_size) > pi->conn->mtu - 10)
+                               rfc.max_pdu_size = cpu_to_le16(pi->conn->mtu - 10);
 
                        pi->remote_mps = le16_to_cpu(rfc.max_pdu_size);
 
@@ -2759,10 +2768,10 @@ static int l2cap_parse_conf_rsp(struct sock *sk, void *rsp, int len, void *data,
                case L2CAP_CONF_MTU:
                        if (val < L2CAP_DEFAULT_MIN_MTU) {
                                *result = L2CAP_CONF_UNACCEPT;
-                               pi->omtu = L2CAP_DEFAULT_MIN_MTU;
+                               pi->imtu = L2CAP_DEFAULT_MIN_MTU;
                        } else
-                               pi->omtu = val;
-                       l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, pi->omtu);
+                               pi->imtu = val;
+                       l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, pi->imtu);
                        break;
 
                case L2CAP_CONF_FLUSH_TO:
@@ -2795,7 +2804,6 @@ static int l2cap_parse_conf_rsp(struct sock *sk, void *rsp, int len, void *data,
        if (*result == L2CAP_CONF_SUCCESS) {
                switch (rfc.mode) {
                case L2CAP_MODE_ERTM:
-                       pi->remote_tx_win   = rfc.txwin_size;
                        pi->retrans_timeout = le16_to_cpu(rfc.retrans_timeout);
                        pi->monitor_timeout = le16_to_cpu(rfc.monitor_timeout);
                        pi->mps    = le16_to_cpu(rfc.max_pdu_size);
@@ -2851,7 +2859,6 @@ static void l2cap_conf_rfc_get(struct sock *sk, void *rsp, int len)
 done:
        switch (rfc.mode) {
        case L2CAP_MODE_ERTM:
-               pi->remote_tx_win   = rfc.txwin_size;
                pi->retrans_timeout = le16_to_cpu(rfc.retrans_timeout);
                pi->monitor_timeout = le16_to_cpu(rfc.monitor_timeout);
                pi->mps    = le16_to_cpu(rfc.max_pdu_size);
@@ -2886,7 +2893,7 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd
        struct l2cap_chan_list *list = &conn->chan_list;
        struct l2cap_conn_req *req = (struct l2cap_conn_req *) data;
        struct l2cap_conn_rsp rsp;
-       struct sock *parent, *uninitialized_var(sk);
+       struct sock *parent, *sk = NULL;
        int result, status = L2CAP_CS_NO_INFO;
 
        u16 dcid = 0, scid = __le16_to_cpu(req->scid);
@@ -2901,6 +2908,8 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd
                goto sendresp;
        }
 
+       bh_lock_sock(parent);
+
        /* Check if the ACL is secure enough (if not SDP) */
        if (psm != cpu_to_le16(0x0001) &&
                                !hci_conn_check_link_mode(conn->hcon)) {
@@ -2995,7 +3004,7 @@ sendresp:
                                        L2CAP_INFO_REQ, sizeof(info), &info);
        }
 
-       if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_REQ_SENT) &&
+       if (sk && !(l2cap_pi(sk)->conf_state & L2CAP_CONF_REQ_SENT) &&
                                result == L2CAP_CR_SUCCESS) {
                u8 buf[128];
                l2cap_pi(sk)->conf_state |= L2CAP_CONF_REQ_SENT;
@@ -3053,6 +3062,14 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd
                break;
 
        default:
+               /* don't delete l2cap channel if sk is owned by user */
+               if (sock_owned_by_user(sk)) {
+                       sk->sk_state = BT_DISCONN;
+                       l2cap_sock_clear_timer(sk);
+                       l2cap_sock_set_timer(sk, HZ / 5);
+                       break;
+               }
+
                l2cap_chan_del(sk, ECONNREFUSED);
                break;
        }
@@ -3061,6 +3078,17 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd
        return 0;
 }
 
+static inline void set_default_fcs(struct l2cap_pinfo *pi)
+{
+       /* FCS is enabled only in ERTM or streaming mode, if one or both
+        * sides request it.
+        */
+       if (pi->mode != L2CAP_MODE_ERTM && pi->mode != L2CAP_MODE_STREAMING)
+               pi->fcs = L2CAP_FCS_NONE;
+       else if (!(pi->conf_state & L2CAP_CONF_NO_FCS_RECV))
+               pi->fcs = L2CAP_FCS_CRC16;
+}
+
 static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd, u16 cmd_len, u8 *data)
 {
        struct l2cap_conf_req *req = (struct l2cap_conf_req *) data;
@@ -3089,7 +3117,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
 
        /* Reject if config buffer is too small. */
        len = cmd_len - sizeof(*req);
-       if (l2cap_pi(sk)->conf_len + len > sizeof(l2cap_pi(sk)->conf_req)) {
+       if (len < 0 || l2cap_pi(sk)->conf_len + len > sizeof(l2cap_pi(sk)->conf_req)) {
                l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP,
                                l2cap_build_conf_rsp(sk, rsp,
                                        L2CAP_CONF_REJECT, flags), rsp);
@@ -3125,9 +3153,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
                goto unlock;
 
        if (l2cap_pi(sk)->conf_state & L2CAP_CONF_INPUT_DONE) {
-               if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_NO_FCS_RECV) ||
-                   l2cap_pi(sk)->fcs != L2CAP_FCS_NONE)
-                       l2cap_pi(sk)->fcs = L2CAP_FCS_CRC16;
+               set_default_fcs(l2cap_pi(sk));
 
                sk->sk_state = BT_CONNECTED;
 
@@ -3143,6 +3169,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
 
        if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_REQ_SENT)) {
                u8 buf[64];
+               l2cap_pi(sk)->conf_state |= L2CAP_CONF_REQ_SENT;
                l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
                                        l2cap_build_conf_req(sk, buf), buf);
                l2cap_pi(sk)->num_conf_req++;
@@ -3215,9 +3242,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
        l2cap_pi(sk)->conf_state |= L2CAP_CONF_INPUT_DONE;
 
        if (l2cap_pi(sk)->conf_state & L2CAP_CONF_OUTPUT_DONE) {
-               if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_NO_FCS_RECV) ||
-                   l2cap_pi(sk)->fcs != L2CAP_FCS_NONE)
-                       l2cap_pi(sk)->fcs = L2CAP_FCS_CRC16;
+               set_default_fcs(l2cap_pi(sk));
 
                sk->sk_state = BT_CONNECTED;
                l2cap_pi(sk)->next_tx_seq = 0;
@@ -3256,6 +3281,15 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd
 
        sk->sk_shutdown = SHUTDOWN_MASK;
 
+       /* don't delete l2cap channel if sk is owned by user */
+       if (sock_owned_by_user(sk)) {
+               sk->sk_state = BT_DISCONN;
+               l2cap_sock_clear_timer(sk);
+               l2cap_sock_set_timer(sk, HZ / 5);
+               bh_unlock_sock(sk);
+               return 0;
+       }
+
        l2cap_chan_del(sk, ECONNRESET);
        bh_unlock_sock(sk);
 
@@ -3278,6 +3312,15 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn, struct l2cap_cmd
        if (!sk)
                return 0;
 
+       /* don't delete l2cap channel if sk is owned by user */
+       if (sock_owned_by_user(sk)) {
+               sk->sk_state = BT_DISCONN;
+               l2cap_sock_clear_timer(sk);
+               l2cap_sock_set_timer(sk, HZ / 5);
+               bh_unlock_sock(sk);
+               return 0;
+       }
+
        l2cap_chan_del(sk, 0);
        bh_unlock_sock(sk);
 
@@ -3300,7 +3343,7 @@ static inline int l2cap_information_req(struct l2cap_conn *conn, struct l2cap_cm
                struct l2cap_info_rsp *rsp = (struct l2cap_info_rsp *) buf;
                rsp->type   = cpu_to_le16(L2CAP_IT_FEAT_MASK);
                rsp->result = cpu_to_le16(L2CAP_IR_SUCCESS);
-               if (enable_ertm)
+               if (!disable_ertm)
                        feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING
                                                         | L2CAP_FEAT_FCS;
                put_unaligned_le32(feat_mask, rsp->data);
@@ -3337,6 +3380,15 @@ static inline int l2cap_information_rsp(struct l2cap_conn *conn, struct l2cap_cm
 
        del_timer(&conn->info_timer);
 
+       if (result != L2CAP_IR_SUCCESS) {
+               conn->info_state |= L2CAP_INFO_FEAT_MASK_REQ_DONE;
+               conn->info_ident = 0;
+
+               l2cap_conn_start(conn);
+
+               return 0;
+       }
+
        if (type == L2CAP_IT_FEAT_MASK) {
                conn->feat_mask = get_unaligned_le32(rsp->data);
 
@@ -4098,11 +4150,10 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control)
                        __mod_retrans_timer();
 
                pi->conn_state &= ~L2CAP_CONN_REMOTE_BUSY;
-               if (pi->conn_state & L2CAP_CONN_SREJ_SENT) {
+               if (pi->conn_state & L2CAP_CONN_SREJ_SENT)
                        l2cap_send_ack(pi);
-               } else {
+               else
                        l2cap_ertm_send(sk);
-               }
        }
 }
 
@@ -4394,6 +4445,8 @@ static inline int l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, str
        if (!sk)
                goto drop;
 
+       bh_lock_sock(sk);
+
        BT_DBG("sk %p, len %d", sk, skb->len);
 
        if (sk->sk_state != BT_BOUND && sk->sk_state != BT_CONNECTED)
@@ -4628,6 +4681,8 @@ static int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 fl
 
        if (flags & ACL_START) {
                struct l2cap_hdr *hdr;
+               struct sock *sk;
+               u16 cid;
                int len;
 
                if (conn->rx_len) {
@@ -4638,7 +4693,8 @@ static int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 fl
                        l2cap_conn_unreliable(conn, ECOMM);
                }
 
-               if (skb->len < 2) {
+               /* Start fragment always begin with Basic L2CAP header */
+               if (skb->len < L2CAP_HDR_SIZE) {
                        BT_ERR("Frame is too short (len %d)", skb->len);
                        l2cap_conn_unreliable(conn, ECOMM);
                        goto drop;
@@ -4646,6 +4702,7 @@ static int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 fl
 
                hdr = (struct l2cap_hdr *) skb->data;
                len = __le16_to_cpu(hdr->len) + L2CAP_HDR_SIZE;
+               cid = __le16_to_cpu(hdr->cid);
 
                if (len == skb->len) {
                        /* Complete frame received */
@@ -4662,6 +4719,19 @@ static int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 fl
                        goto drop;
                }
 
+               sk = l2cap_get_chan_by_scid(&conn->chan_list, cid);
+
+               if (sk && l2cap_pi(sk)->imtu < len - L2CAP_HDR_SIZE) {
+                       BT_ERR("Frame exceeding recv MTU (len %d, MTU %d)",
+                                       len, l2cap_pi(sk)->imtu);
+                       bh_unlock_sock(sk);
+                       l2cap_conn_unreliable(conn, ECOMM);
+                       goto drop;
+               }
+
+               if (sk)
+                       bh_unlock_sock(sk);
+
                /* Allocate skb for the complete frame (with header) */
                conn->rx_skb = bt_skb_alloc(len, GFP_ATOMIC);
                if (!conn->rx_skb)
@@ -4788,8 +4858,10 @@ static int __init l2cap_init(void)
                return err;
 
        _busy_wq = create_singlethread_workqueue("l2cap");
-       if (!_busy_wq)
-               goto error;
+       if (!_busy_wq) {
+               proto_unregister(&l2cap_proto);
+               return -ENOMEM;
+       }
 
        err = bt_sock_register(BTPROTO_L2CAP, &l2cap_sock_family_ops);
        if (err < 0) {
@@ -4817,6 +4889,7 @@ static int __init l2cap_init(void)
        return 0;
 
 error:
+       destroy_workqueue(_busy_wq);
        proto_unregister(&l2cap_proto);
        return err;
 }
@@ -4848,8 +4921,8 @@ EXPORT_SYMBOL(l2cap_load);
 module_init(l2cap_init);
 module_exit(l2cap_exit);
 
-module_param(enable_ertm, bool, 0644);
-MODULE_PARM_DESC(enable_ertm, "Enable enhanced retransmission mode");
+module_param(disable_ertm, bool, 0644);
+MODULE_PARM_DESC(disable_ertm, "Disable enhanced retransmission mode");
 
 MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
 MODULE_DESCRIPTION("Bluetooth L2CAP ver " VERSION);