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

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Message-ID: <20240407131426.1053736-4-sashal@kernel.org>
Date: Sun,  7 Apr 2024 09:14:24 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: linke li <lilinke99@...com>,
	Eric Dumazet <edumazet@...gle.com>,
	"David S . Miller" <davem@...emloft.net>,
	Sasha Levin <sashal@...nel.org>,
	kuba@...nel.org,
	pabeni@...hat.com,
	kuniyu@...zon.com,
	willemb@...gle.com,
	wuyun.abel@...edance.com,
	leitao@...ian.org,
	alexander@...alicyn.com,
	dhowells@...hat.com,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 4/5] net: mark racy access on sk->sk_rcvbuf

From: linke li <lilinke99@...com>

[ 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@...com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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