diff options
| author | Tom Marshall <tdm.code@gmail.com> | 2010-09-21 02:42:05 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-09-21 02:42:05 +0400 |
| commit | a4d258036ed9b2a1811c3670c6099203a0f284a0 (patch) | |
| tree | 58412022664aef745a99d254d20cf1a66aabda44 | |
| parent | 9828e6e6e3f19efcb476c567b9999891d051f52f (diff) | |
| download | linux-a4d258036ed9b2a1811c3670c6099203a0f284a0.tar.xz | |
tcp: Fix race in tcp_poll
If a RST comes in immediately after checking sk->sk_err, tcp_poll will
return POLLIN but not POLLOUT. Fix this by checking sk->sk_err at the end
of tcp_poll. Additionally, ensure the correct order of operations on SMP
machines with memory barriers.
Signed-off-by: Tom Marshall <tdm.code@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/tcp.c | 7 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 2 |
2 files changed, 7 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 3fb1428e526e..95d75d443927 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -386,8 +386,6 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) */ mask = 0; - if (sk->sk_err) - mask = POLLERR; /* * POLLHUP is certainly not done right. But poll() doesn't @@ -457,6 +455,11 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) if (tp->urg_data & TCP_URG_VALID) mask |= POLLPRI; } + /* This barrier is coupled with smp_wmb() in tcp_reset() */ + smp_rmb(); + if (sk->sk_err) + mask |= POLLERR; + return mask; } EXPORT_SYMBOL(tcp_poll); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e663b78a2ef6..149e79ac2891 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4048,6 +4048,8 @@ static void tcp_reset(struct sock *sk) default: sk->sk_err = ECONNRESET; } + /* This barrier is coupled with smp_rmb() in tcp_poll() */ + smp_wmb(); if (!sock_flag(sk, SOCK_DEAD)) sk->sk_error_report(sk); |