linux-kernel - [PATCH net-next 2/4] net: bridge: mcast: fix memcpy with u64

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Message-ID: <20260120092137.2161162-3-mmyangfl@gmail.com>
Date: Tue, 20 Jan 2026 17:21:30 +0800
From: David Yang <mmyangfl@...il.com>
To: netdev@...r.kernel.org
Cc: David Yang <mmyangfl@...il.com>,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	Ido Schimmel <idosch@...dia.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	bridge@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next 2/4] net: bridge: mcast: fix memcpy with u64_stats

On 64bit arches, struct u64_stats_sync is empty and provides no help
against load/store tearing. memcpy() should not be considered atomic
against u64 values. Use u64_stats_copy() instead.

Signed-off-by: David Yang <mmyangfl@...il.com>
---
 net/bridge/br_multicast.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index d55a4ab87837..dccae08b4f4c 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -5201,7 +5201,7 @@ void br_multicast_get_stats(const struct net_bridge *br,
 
 		do {
 			start = u64_stats_fetch_begin(&cpu_stats->syncp);
-			memcpy(&temp, &cpu_stats->mstats, sizeof(temp));
+			u64_stats_copy(&temp, &cpu_stats->mstats, sizeof(temp));
 		} while (u64_stats_fetch_retry(&cpu_stats->syncp, start));
 
 		mcast_stats_add_dir(tdst.igmp_v1queries, temp.igmp_v1queries);
-- 
2.51.0