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| author | Eric Dumazet <edumazet@google.com> | 2019-10-10 20:17:38 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-10-13 10:13:08 -0700 |
| commit | d983ea6f16b835dcde2ee9a58a1e764ce68bfccc (patch) | |
| tree | 2bc283f36a6769e0247c49420f0c2149f147f08c /net/ipv4/tcp_input.c | |
| parent | 8caf8a91f34d55e8e3b1355ee8d658cb472146e2 (diff) | |
| download | lwn-d983ea6f16b835dcde2ee9a58a1e764ce68bfccc.tar.gz lwn-d983ea6f16b835dcde2ee9a58a1e764ce68bfccc.zip | |
tcp: add rcu protection around tp->fastopen_rsk
Both tcp_v4_err() and tcp_v6_err() do the following operations
while they do not own the socket lock :
fastopen = tp->fastopen_rsk;
snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
The problem is that without appropriate barrier, the compiler
might reload tp->fastopen_rsk and trigger a NULL deref.
request sockets are protected by RCU, we can simply add
the missing annotations and barriers to solve the issue.
Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 3578357abe30..5f9b102c3b55 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2666,7 +2666,7 @@ static void tcp_process_loss(struct sock *sk, int flag, int num_dupack, struct tcp_sock *tp = tcp_sk(sk); bool recovered = !before(tp->snd_una, tp->high_seq); - if ((flag & FLAG_SND_UNA_ADVANCED || tp->fastopen_rsk) && + if ((flag & FLAG_SND_UNA_ADVANCED || rcu_access_pointer(tp->fastopen_rsk)) && tcp_try_undo_loss(sk, false)) return; @@ -2990,7 +2990,7 @@ void tcp_rearm_rto(struct sock *sk) /* If the retrans timer is currently being used by Fast Open * for SYN-ACK retrans purpose, stay put. */ - if (tp->fastopen_rsk) + if (rcu_access_pointer(tp->fastopen_rsk)) return; if (!tp->packets_out) { @@ -6087,6 +6087,8 @@ reset_and_undo: static void tcp_rcv_synrecv_state_fastopen(struct sock *sk) { + struct request_sock *req; + tcp_try_undo_loss(sk, false); /* Reset rtx states to prevent spurious retransmits_timed_out() */ @@ -6096,7 +6098,9 @@ static void tcp_rcv_synrecv_state_fastopen(struct sock *sk) /* Once we leave TCP_SYN_RECV or TCP_FIN_WAIT_1, * we no longer need req so release it. */ - reqsk_fastopen_remove(sk, tcp_sk(sk)->fastopen_rsk, false); + req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk, + lockdep_sock_is_held(sk)); + reqsk_fastopen_remove(sk, req, false); /* Re-arm the timer because data may have been sent out. * This is similar to the regular data transmission case @@ -6171,7 +6175,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) tcp_mstamp_refresh(tp); tp->rx_opt.saw_tstamp = 0; - req = tp->fastopen_rsk; + req = rcu_dereference_protected(tp->fastopen_rsk, + lockdep_sock_is_held(sk)); if (req) { bool req_stolen; |