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

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

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230509173131.3263780-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-05-09 17:31:31 +00:00 committed by Jakub Kicinski
parent cdc2e28e21
commit 5bca1d081f
1 changed files with 10 additions and 5 deletions
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15
net/core/datagram.c
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@ -807,18 +807,21 @@ __poll_t datagram_poll(struct file *file, struct socket *sock,
{
struct sock *sk = sock->sk;
__poll_t mask;
u8 shutdown;
sock_poll_wait(file, sock, wait);
mask = 0;
/* 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 |
(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;
if (sk->sk_shutdown == SHUTDOWN_MASK)
if (shutdown == SHUTDOWN_MASK)
mask |= EPOLLHUP;
/* readable? */
@ -827,10 +830,12 @@ __poll_t datagram_poll(struct file *file, struct socket *sock,
/* Connection-based need to check for termination and startup */
if (connection_based(sk)) {
if (sk->sk_state == TCP_CLOSE)
int state = READ_ONCE(sk->sk_state);
if (state == TCP_CLOSE)
mask |= EPOLLHUP;
/* connection hasn't started yet? */
if (sk->sk_state == TCP_SYN_SENT)
if (state == TCP_SYN_SENT)
return mask;
}