Commit 5bca1d08 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski

net: datagram: fix data-races in datagram_poll()

datagram_poll() runs locklessly, we should add READ_ONCE()
annotations while reading sk->sk_err, sk->sk_shutdown and sk->sk_state.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230509173131.3263780-1-edumazet@google.comSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent cdc2e28e
...@@ -807,18 +807,21 @@ __poll_t datagram_poll(struct file *file, struct socket *sock, ...@@ -807,18 +807,21 @@ __poll_t datagram_poll(struct file *file, struct socket *sock,
{ {
struct sock *sk = sock->sk; struct sock *sk = sock->sk;
__poll_t mask; __poll_t mask;
u8 shutdown;
sock_poll_wait(file, sock, wait); sock_poll_wait(file, sock, wait);
mask = 0; mask = 0;
/* exceptional events? */ /* exceptional events? */
if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue)) if (READ_ONCE(sk->sk_err) ||
!skb_queue_empty_lockless(&sk->sk_error_queue))
mask |= EPOLLERR | mask |= EPOLLERR |
(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0); (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
if (sk->sk_shutdown & RCV_SHUTDOWN) shutdown = READ_ONCE(sk->sk_shutdown);
if (shutdown & RCV_SHUTDOWN)
mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM; mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
if (sk->sk_shutdown == SHUTDOWN_MASK) if (shutdown == SHUTDOWN_MASK)
mask |= EPOLLHUP; mask |= EPOLLHUP;
/* readable? */ /* readable? */
...@@ -827,10 +830,12 @@ __poll_t datagram_poll(struct file *file, struct socket *sock, ...@@ -827,10 +830,12 @@ __poll_t datagram_poll(struct file *file, struct socket *sock,
/* Connection-based need to check for termination and startup */ /* Connection-based need to check for termination and startup */
if (connection_based(sk)) { if (connection_based(sk)) {
if (sk->sk_state == TCP_CLOSE) int state = READ_ONCE(sk->sk_state);
if (state == TCP_CLOSE)
mask |= EPOLLHUP; mask |= EPOLLHUP;
/* connection hasn't started yet? */ /* connection hasn't started yet? */
if (sk->sk_state == TCP_SYN_SENT) if (state == TCP_SYN_SENT)
return mask; return mask;
} }
......
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