@@ -704,7 +704,8 @@ release_sk1:
outside socket context is ugly, certainly. What can I do?
*/
-static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+static void tcp_v4_send_ack(struct net *net,
+ struct sk_buff *skb, u32 seq, u32 ack,
u32 win, u32 tsval, u32 tsecr, int oif,
struct tcp_md5sig_key *key,
int reply_flags, u8 tos)
@@ -719,7 +720,6 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
];
} rep;
struct ip_reply_arg arg;
- struct net *net = dev_net(skb_dst(skb)->dev);
memset(&rep.th, 0, sizeof(struct tcphdr));
memset(&arg, 0, sizeof(arg));
@@ -781,7 +781,8 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
struct inet_timewait_sock *tw = inet_twsk(sk);
struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
- tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
+ tcp_v4_send_ack(sock_net(sk), skb,
+ tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
tcp_time_stamp + tcptw->tw_ts_offset,
tcptw->tw_ts_recent,
@@ -800,8 +801,10 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
* sk->sk_state == TCP_SYN_RECV -> for Fast Open.
*/
- tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
- tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
+ u32 seq = (sk->sk_state == TCP_LISTEN) ? tcp_rsk(req)->snt_isn + 1 :
+ tcp_sk(sk)->snd_nxt;
+
+ tcp_v4_send_ack(sock_net(sk), skb, seq,
tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
tcp_time_stamp,
req->ts_recent,
This is a note to let you know that I have just added a patch titled tcp: fix NULL deref in tcp_v4_send_ack() to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt16. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From a835fe4a03dc9501cfe2b249345ef2c239866aa6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@google.com> Date: Thu, 21 Jan 2016 08:02:54 -0800 Subject: tcp: fix NULL deref in tcp_v4_send_ack() [ Upstream commit e62a123b8ef7c5dc4db2c16383d506860ad21b47 ] Neal reported crashes with this stack trace : RIP: 0010:[<ffffffff8c57231b>] tcp_v4_send_ack+0x41/0x20f ... CR2: 0000000000000018 CR3: 000000044005c000 CR4: 00000000001427e0 ... [<ffffffff8c57258e>] tcp_v4_reqsk_send_ack+0xa5/0xb4 [<ffffffff8c1a7caa>] tcp_check_req+0x2ea/0x3e0 [<ffffffff8c19e420>] tcp_rcv_state_process+0x850/0x2500 [<ffffffff8c1a6d21>] tcp_v4_do_rcv+0x141/0x330 [<ffffffff8c56cdb2>] sk_backlog_rcv+0x21/0x30 [<ffffffff8c098bbd>] tcp_recvmsg+0x75d/0xf90 [<ffffffff8c0a8700>] inet_recvmsg+0x80/0xa0 [<ffffffff8c17623e>] sock_aio_read+0xee/0x110 [<ffffffff8c066fcf>] do_sync_read+0x6f/0xa0 [<ffffffff8c0673a1>] SyS_read+0x1e1/0x290 [<ffffffff8c5ca262>] system_call_fastpath+0x16/0x1b The problem here is the skb we provide to tcp_v4_send_ack() had to be parked in the backlog of a new TCP fastopen child because this child was owned by the user at the time an out of window packet arrived. Before queuing a packet, TCP has to set skb->dev to NULL as the device could disappear before packet is removed from the queue. Fix this issue by using the net pointer provided by the socket (being a timewait or a request socket). IPv6 is immune to the bug : tcp_v6_send_response() already gets the net pointer from the socket if provided. Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path") Reported-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jerry Chu <hkchu@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/ipv4/tcp_ipv4.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) -- 2.7.0