From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 5bca1d081f44c9443e61841842ce4e9179d327b6 ]
datagram_poll() runs locklessly, we should add READ_ONCE()
annotations while reading sk->sk_err, sk->sk_shutdown and sk->sk_state.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230509173131.3263780-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/core/datagram.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/net/core/datagram.c b/net/core/datagram.c
index e4ff2db40c981..8dabb9a74cb17 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -799,18 +799,21 @@ __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? */
@@ -819,10 +822,12 @@ __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;
}
--
2.39.2
