This patch now always passes msg->msg_namelen as 0. recvmsg handlers must
set msg_namelen to the proper size <= sizeof(struct sockaddr_storage)
to return msg_name to the user.

This prevents numerous uninitialized memory leaks we had in the
recvmsg handlers and makes it harder for new code to accidentally leak
uninitialized memory.

Optimize for the case recvfrom is called with NULL as address. We don't
need to copy the address at all, so set it to NULL before invoking the
recvmsg handler. We can do so, because all the recvmsg handlers must
cope with the case a plain read() is called on them. read() also sets
msg_name to NULL.

Also document these changes in include/linux/net.h as suggested by David
Miller.

Changes since RFC:

Set msg->msg_name = NULL if user specified a NULL in msg_name but had a
non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't
affect sendto as it would bail out earlier while trying to copy-in the
address. It also more naturally reflects the logic by the callers of
verify_iovec.

With this change in place I could remove "
if (!uaddr || msg_sys->msg_namelen == 0)
	msg->msg_name = NULL
".

This change does not alter the user visible error logic as we ignore
msg_namelen as long as msg_name is NULL.

Also remove two unnecessary curly brackets in ___sys_recvmsg and change
comments to netdev style.

Cc: David Miller <davem@davemloft.net>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

L2CAP socket validates proper bdaddr_type for connect, so this
patch fixes to set explictly bdaddr_type for RFCOMM connect.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

L2CAP socket bind checks its bdaddr type but RFCOMM kernel thread
does not assign proper bdaddr type for L2CAP sock. This can cause
that RFCOMM failure.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

The commit 94a86df01082557e2de45865e538d7fb6c46231c seem to have
uncovered a long standing bug that did not trigger so far.

BUG: unable to handle kernel paging request at 00000009dd503502
IP: [<ffffffff815b1868>] rfcomm_sock_getsockopt+0x128/0x200
PGD 0
Oops: 0000 [#1] SMP
Modules linked in: ath5k ath mac80211 cfg80211
CPU: 2 PID: 1459 Comm: bluetoothd Not tainted 3.11.0-133163-gcebd830 #2
Hardware name: System manufacturer System Product Name/P6T DELUXE V2, BIOS
1202    12/22/2010
task: ffff8803304106a0 ti: ffff88033046a000 task.ti: ffff88033046a000
RIP: 0010:[<ffffffff815b1868>]  [<ffffffff815b1868>]
rfcomm_sock_getsockopt+0x128/0x200
RSP: 0018:ffff88033046bed8  EFLAGS: 00010246
RAX: 00000009dd503502 RBX: 0000000000000003 RCX: 00007fffa2ed5548
RDX: 0000000000000003 RSI: 0000000000000012 RDI: ffff88032fd37480
RBP: ffff88033046bf28 R08: 00007fffa2ed554c R09: ffff88032f5707d8
R10: 00007fffa2ed5548 R11: 0000000000000202 R12: ffff880330bbd000
R13: 00007fffa2ed5548 R14: 0000000000000003 R15: 00007fffa2ed554c
FS:  00007fc44cfac700(0000) GS:ffff88033fc80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000009dd503502 CR3: 00000003304c2000 CR4: 00000000000007e0
Stack:
ffff88033046bf28 ffffffff815b0f2f ffff88033046bf18 0002ffff81105ef6
0000000600000000 ffff88032fd37480 0000000000000012 00007fffa2ed5548
0000000000000003 00007fffa2ed554c ffff88033046bf78 ffffffff814c0380
Call Trace:
[<ffffffff815b0f2f>] ? rfcomm_sock_setsockopt+0x5f/0x190
[<ffffffff814c0380>] SyS_getsockopt+0x60/0xb0
[<ffffffff815e0852>] system_call_fastpath+0x16/0x1b
Code: 02 00 00 00 0f 47 d0 4c 89 ef e8 74 13 cd ff 83 f8 01 19 c9 f7 d1 83 e1
f2 e9 4b ff ff ff 0f 1f 44 00 00 49 8b 84 24 70 02 00 00 <4c> 8b 30 4c 89 c0 e8
2d 19 cd ff 85 c0 49 89 d7 b9 f2 ff ff ff
RIP  [<ffffffff815b1868>] rfcomm_sock_getsockopt+0x128/0x200
RSP <ffff88033046bed8>
CR2: 00000009dd503502

It triggers in the following segment of the code:

0x1313 is in rfcomm_sock_getsockopt (net/bluetooth/rfcomm/sock.c:743).
738
739	static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __user *optval, int __user *optlen)
740	{
741		struct sock *sk = sock->sk;
742		struct rfcomm_conninfo cinfo;
743		struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn;
744		int len, err = 0;
745		u32 opt;
746
747		BT_DBG("sk %p", sk);

The l2cap_pi(sk) is wrong here since it should have been rfcomm_pi(sk),
but that socket of course does not contain the low-level connection
details requested here.

Tracking down the actual offending commit, it seems that this has been
introduced when doing some L2CAP refactoring:

commit 8c1d787be4b62d2d1b6f04953eca4bcf7c839d44
Author: Gustavo F. Padovan <padovan@profusion.mobi>
Date:   Wed Apr 13 20:23:55 2011 -0300

@@ -743,6 +743,7 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u
        struct sock *sk = sock->sk;
        struct sock *l2cap_sk;
        struct rfcomm_conninfo cinfo;
+       struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn;
        int len, err = 0;
        u32 opt;

@@ -787,8 +788,8 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u

                l2cap_sk = rfcomm_pi(sk)->dlc->session->sock->sk;

-               cinfo.hci_handle = l2cap_pi(l2cap_sk)->conn->hcon->handle;
-               memcpy(cinfo.dev_class, l2cap_pi(l2cap_sk)->conn->hcon->dev_class, 3);
+               cinfo.hci_handle = conn->hcon->handle;
+               memcpy(cinfo.dev_class, conn->hcon->dev_class, 3);

The l2cap_sk got accidentally mixed into the sk (which is RFCOMM) and
now causing a problem within getsocketopt() system call. To fix this,
just re-introduce l2cap_sk and make sure the right socket is used for
the low-level connection details.

Reported-by: Fabio Rossi <rossi.f@inwind.it>
Reported-by: Janusz Dziedzic <janusz.dziedzic@gmail.com>
Tested-by: Janusz Dziedzic <janusz.dziedzic@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

Make sure to use IS_ERR_OR_NULL for checking the existing of the root
debugfs dentry bt_debugfs.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

The address information of RFCOMM sockets should be stored in its
own socket structure. Trying to generalize them is not helpful since
different transports have different address types.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

The L2CAP socket structure does not contain the address information
anymore. They need to be accessed through the L2CAP channel.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

Conflicts:
	net/bluetooth/hci_core.c