[PATCH AUTOSEL 4.19 4/5] net: mark racy access on sk->sk_rcvbuf

From: Sasha Levin
Date: Sun Apr 07 2024 - 09:41:48 EST


From: linke li <lilinke99@xxxxxx>

[ Upstream commit c2deb2e971f5d9aca941ef13ee05566979e337a4 ]

sk->sk_rcvbuf in __sock_queue_rcv_skb() and __sk_receive_skb() can be
changed by other threads. Mark this as benign using READ_ONCE().

This patch is aimed at reducing the number of benign races reported by
KCSAN in order to focus future debugging effort on harmful races.

Signed-off-by: linke li <lilinke99@xxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/core/sock.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 62d169bcfcfa1..dd7cee54b66cc 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -404,7 +404,7 @@ int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
unsigned long flags;
struct sk_buff_head *list = &sk->sk_receive_queue;

- if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) {
+ if (atomic_read(&sk->sk_rmem_alloc) >= READ_ONCE(sk->sk_rcvbuf)) {
atomic_inc(&sk->sk_drops);
trace_sock_rcvqueue_full(sk, skb);
return -ENOMEM;
@@ -456,7 +456,7 @@ int __sk_receive_skb(struct sock *sk, struct sk_buff *skb,

skb->dev = NULL;

- if (sk_rcvqueues_full(sk, sk->sk_rcvbuf)) {
+ if (sk_rcvqueues_full(sk, READ_ONCE(sk->sk_rcvbuf))) {
atomic_inc(&sk->sk_drops);
goto discard_and_relse;
}
--
2.43.0