tcp: fix TFO regression

Fengguang Wu reported various panics and bisected to commit
8336886f786fdac (tcp: TCP Fast Open Server - support TFO listeners)

Fix this by making sure socket is a TCP socket before accessing TFO data
structures.

[  233.046014] kfree_debugcheck: out of range ptr ea6000000bb8h.
[  233.047399] ------------[ cut here ]------------
[  233.048393] kernel BUG at /c/kernel-tests/src/stable/mm/slab.c:3074!
[  233.048393] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
[  233.048393] Modules linked in:
[  233.048393] CPU 0
[  233.048393] Pid: 3929, comm: trinity-watchdo Not tainted 3.6.0-rc3+
#4192 Bochs Bochs
[  233.048393] RIP: 0010:[<ffffffff81169653>]  [<ffffffff81169653>]
kfree_debugcheck+0x27/0x2d
[  233.048393] RSP: 0018:ffff88000facbca8  EFLAGS: 00010092
[  233.048393] RAX: 0000000000000031 RBX: 0000ea6000000bb8 RCX:
00000000a189a188
[  233.048393] RDX: 000000000000a189 RSI: ffffffff8108ad32 RDI:
ffffffff810d30f9
[  233.048393] RBP: ffff88000facbcb8 R08: 0000000000000002 R09:
ffffffff843846f0
[  233.048393] R10: ffffffff810ae37c R11: 0000000000000908 R12:
0000000000000202
[  233.048393] R13: ffffffff823dbd5a R14: ffff88000ec5bea8 R15:
ffffffff8363c780
[  233.048393] FS:  00007faa6899c700(0000) GS:ffff88001f200000(0000)
knlGS:0000000000000000
[  233.048393] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  233.048393] CR2: 00007faa6841019c CR3: 0000000012c82000 CR4:
00000000000006f0
[  233.048393] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[  233.048393] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[  233.048393] Process trinity-watchdo (pid: 3929, threadinfo
ffff88000faca000, task ffff88000faec600)
[  233.048393] Stack:
[  233.048393]  0000000000000000 0000ea6000000bb8 ffff88000facbce8
ffffffff8116ad81
[  233.048393]  ffff88000ff588a0 ffff88000ff58850 ffff88000ff588a0
0000000000000000
[  233.048393]  ffff88000facbd08 ffffffff823dbd5a ffffffff823dbcb0
ffff88000ff58850
[  233.048393] Call Trace:
[  233.048393]  [<ffffffff8116ad81>] kfree+0x5f/0xca
[  233.048393]  [<ffffffff823dbd5a>] inet_sock_destruct+0xaa/0x13c
[  233.048393]  [<ffffffff823dbcb0>] ? inet_sk_rebuild_header
+0x319/0x319
[  233.048393]  [<ffffffff8231c307>] __sk_free+0x21/0x14b
[  233.048393]  [<ffffffff8231c4bd>] sk_free+0x26/0x2a
[  233.048393]  [<ffffffff825372db>] sctp_close+0x215/0x224
[  233.048393]  [<ffffffff810d6835>] ? lock_release+0x16f/0x1b9
[  233.048393]  [<ffffffff823daf12>] inet_release+0x7e/0x85
[  233.048393]  [<ffffffff82317d15>] sock_release+0x1f/0x77
[  233.048393]  [<ffffffff82317d94>] sock_close+0x27/0x2b
[  233.048393]  [<ffffffff81173bbe>] __fput+0x101/0x20a
[  233.048393]  [<ffffffff81173cd5>] ____fput+0xe/0x10
[  233.048393]  [<ffffffff810a3794>] task_work_run+0x5d/0x75
[  233.048393]  [<ffffffff8108da70>] do_exit+0x290/0x7f5
[  233.048393]  [<ffffffff82707415>] ? retint_swapgs+0x13/0x1b
[  233.048393]  [<ffffffff8108e23f>] do_group_exit+0x7b/0xba
[  233.048393]  [<ffffffff8108e295>] sys_exit_group+0x17/0x17
[  233.048393]  [<ffffffff8270de10>] tracesys+0xdd/0xe2
[  233.048393] Code: 59 01 5d c3 55 48 89 e5 53 41 50 0f 1f 44 00 00 48
89 fb e8 d4 b0 f0 ff 84 c0 75 11 48 89 de 48 c7 c7 fc fa f7 82 e8 0d 0f
57 01 <0f> 0b 5f 5b 5d c3 55 48 89 e5 0f 1f 44 00 00 48 63 87 d8 00 00
[  233.048393] RIP  [<ffffffff81169653>] kfree_debugcheck+0x27/0x2d
[  233.048393]  RSP <ffff88000facbca8>

Reported-by: Fengguang Wu <wfg@linux.intel.com>
Tested-by: Fengguang Wu <wfg@linux.intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: "H.K. Jerry Chu" <hkchu@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: H.K. Jerry Chu <hkchu@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -149,11 +149,8 @@ void inet_sock_destruct(struct sock *sk)
 		pr_err("Attempt to release alive inet socket %p\n", sk);
 		return;
 	}
-	if (sk->sk_type == SOCK_STREAM) {
-		struct fastopen_queue *fastopenq =
-			inet_csk(sk)->icsk_accept_queue.fastopenq;
-		kfree(fastopenq);
-	}
+	if (sk->sk_protocol == IPPROTO_TCP)
+		kfree(inet_csk(sk)->icsk_accept_queue.fastopenq);
 
 	WARN_ON(atomic_read(&sk->sk_rmem_alloc));
 	WARN_ON(atomic_read(&sk->sk_wmem_alloc));

net/ipv4/inet_connection_sock.c

@@ -314,7 +314,7 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 	newsk = req->sk;
 
 	sk_acceptq_removed(sk);
-	if (sk->sk_type == SOCK_STREAM && queue->fastopenq != NULL) {
+	if (sk->sk_protocol == IPPROTO_TCP && queue->fastopenq != NULL) {
 		spin_lock_bh(&queue->fastopenq->lock);
 		if (tcp_rsk(req)->listener) {
 			/* We are still waiting for the final ACK from 3WHS
@@ -775,7 +775,7 @@ void inet_csk_listen_stop(struct sock *sk)
 
 		percpu_counter_inc(sk->sk_prot->orphan_count);
 
-		if (sk->sk_type == SOCK_STREAM && tcp_rsk(req)->listener) {
+		if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->listener) {
 			BUG_ON(tcp_sk(child)->fastopen_rsk != req);
 			BUG_ON(sk != tcp_rsk(req)->listener);