diff options
| author | Tom Marshall <tdm.code@gmail.com> | 2010-09-20 15:42:05 -0700 |
|---|---|---|
| committer | Paul Gortmaker <paul.gortmaker@windriver.com> | 2011-01-06 18:08:14 -0500 |
| commit | 6e029a079025b66a554708d869af455715ecf5cb (patch) | |
| tree | 7a733dfeb275da7ad7a313e8f17ce1c03ae569ad | |
| parent | a621db98fc8cc7b5b513a51ee93df75537256850 (diff) | |
| download | linux-stable-6e029a079025b66a554708d869af455715ecf5cb.tar.gz | |
tcp: Fix race in tcp_poll
commit a4d258036ed9b2a1811c3670c6099203a0f284a0 upstream.
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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
| -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 1b409243cd0e..3fa16d933fde 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -388,8 +388,6 @@ 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 @@ -459,6 +457,11 @@ 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; } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f240f57b2199..dd0c9af58ffc 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4040,6 +4040,8 @@ 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); |