From 68315801dbf3ab2001679fd2074c9dc5dcf87dfa Mon Sep 17 00:00:00 2001 From: James Chapman Date: Wed, 25 Jan 2012 02:39:05 +0000 Subject: [PATCH] l2tp: l2tp_ip - fix possible oops on packet receive When a packet is received on an L2TP IP socket (L2TPv3 IP link encapsulation), the l2tpip socket's backlog_rcv function calls xfrm4_policy_check(). This is not necessary, since it was called before the skb was added to the backlog. With CONFIG_NET_NS enabled, xfrm4_policy_check() will oops if skb->dev is null, so this trivial patch removes the call. This bug has always been present, but only when CONFIG_NET_NS is enabled does it cause problems. Most users are probably using UDP encapsulation for L2TP, hence the problem has only recently surfaced. EIP: 0060:[] EFLAGS: 00210246 CPU: 0 EIP is at l2tp_ip_recvmsg+0xd4/0x2a7 EAX: 00000001 EBX: d77b5180 ECX: 00000000 EDX: 00200246 ESI: 00000000 EDI: d63cbd30 EBP: d63cbd18 ESP: d63cbcf4 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 Call Trace: [] sock_common_recvmsg+0x31/0x46 [] __sock_recvmsg_nosec+0x45/0x4d [] __sock_recvmsg+0x31/0x3b [] sock_recvmsg+0x96/0xab [] ? might_fault+0x47/0x81 [] ? might_fault+0x47/0x81 [] ? _copy_from_user+0x31/0x115 [] ? copy_from_user+0x8/0xa [] ? verify_iovec+0x3e/0x78 [] __sys_recvmsg+0x10a/0x1aa [] ? sock_recvmsg+0x0/0xab [] ? __lock_acquire+0xbdf/0xbee [] ? do_page_fault+0x193/0x375 [] ? fcheck_files+0x9b/0xca [] ? fget_light+0x2a/0x9c [] sys_recvmsg+0x2b/0x43 [] sys_socketcall+0x16d/0x1a5 [] ? trace_hardirqs_on_thunk+0xc/0x10 [] sysenter_do_call+0x12/0x38 Code: c6 05 8c ea a8 c1 01 e8 0c d4 d9 ff 85 f6 74 07 3e ff 86 80 00 00 00 b9 17 b6 2b c1 ba 01 00 00 00 b8 78 ed 48 c1 e8 23 f6 d9 ff 76 0c 68 28 e3 30 c1 68 2d 44 41 c1 e8 89 57 01 00 83 c4 0c Signed-off-by: James Chapman Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/l2tp/l2tp_ip.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index d21e7ebd91ca..55670ec3cd0f 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -393,11 +393,6 @@ static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb) { int rc; - if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) - goto drop; - - nf_reset(skb); - /* Charge it to the socket, dropping if the queue is full. */ rc = sock_queue_rcv_skb(sk, skb); if (rc < 0) -- 2.20.1