netdev - [PATCH v1 net] netlink: Fix rmem check in netlink_broadcast

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Message-ID: <20250711053208.2965945-1-kuniyu@google.com>
Date: Fri, 11 Jul 2025 05:32:07 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
	Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: [PATCH v1 net] netlink: Fix rmem check in netlink_broadcast_deliver().

We need to allow queuing at least one skb even when skb is
larger than sk->sk_rcvbuf.

The cited commit made a mistake while converting a condition
in netlink_broadcast_deliver().

Let's correct the rmem check for the allow-one-skb rule.

Fixes: ae8f160e7eb24 ("netlink: Fix wraparounds of sk->sk_rmem_alloc.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
 net/netlink/af_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 79fbaf7333ce2..2d107a8a75d99 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1395,7 +1395,7 @@ static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
 	rmem = atomic_add_return(skb->truesize, &sk->sk_rmem_alloc);
 	rcvbuf = READ_ONCE(sk->sk_rcvbuf);
 
-	if ((rmem != skb->truesize || rmem <= rcvbuf) &&
+	if ((rmem == skb->truesize || rmem <= rcvbuf) &&
 	    !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
 		netlink_skb_set_owner_r(skb, sk);
 		__netlink_sendskb(sk, skb);
-- 
2.50.0.727.gbf7dc18ff4-goog