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| author | Eric Dumazet <edumazet@google.com> | 2015-10-22 08:20:46 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-10-23 05:42:21 -0700 |
| commit | 5e0724d027f0548511a2165a209572d48fe7a4c8 (patch) | |
| tree | 709301be9b56652004047b89f4467b3c917814cd /net/ipv4/syncookies.c | |
| parent | 7b1311807f3d3eb8bef3ccc53127838b3bea3771 (diff) | |
| download | linux-5e0724d027f0548511a2165a209572d48fe7a4c8.tar.gz linux-5e0724d027f0548511a2165a209572d48fe7a4c8.tar.bz2 linux-5e0724d027f0548511a2165a209572d48fe7a4c8.zip | |
tcp/dccp: fix hashdance race for passive sessions
Multiple cpus can process duplicates of incoming ACK messages
matching a SYN_RECV request socket. This is a rare event under
normal operations, but definitely can happen.
Only one must win the race, otherwise corruption would occur.
To fix this without adding new atomic ops, we use logic in
inet_ehash_nolisten() to detect the request was present in the same
ehash bucket where we try to insert the new child.
If request socket was not found, we have to undo the child creation.
This actually removes a spin_lock()/spin_unlock() pair in
reqsk_queue_unlink() for the fast path.
Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/syncookies.c')
| -rw-r--r-- | net/ipv4/syncookies.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 4c0892badb8b..4cbe9f0a4281 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -221,8 +221,10 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, { struct inet_connection_sock *icsk = inet_csk(sk); struct sock *child; + bool own_req; - child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst); + child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, + NULL, &own_req); if (child) { atomic_set(&req->rsk_refcnt, 1); sock_rps_save_rxhash(child, skb); |