netdev - [PATCH net] inet: shrink struct flowi

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Message-ID: <20231025141037.3448203-1-edumazet@google.com>
Date: Wed, 25 Oct 2023 14:10:37 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, wenxu <wenxu@...oud.cn>
Subject: [PATCH net] inet: shrink struct flowi_common

I am looking at syzbot reports triggering kernel stack overflows
involving a cascade of ipvlan devices.

We can save 8 bytes in struct flowi_common.

This patch alone will not fix the issue, but is a start.

Fixes: 24ba14406c5c ("route: Add multipath_hash in flowi_common to make user-define hash")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: wenxu <wenxu@...oud.cn>
---
 include/net/flow.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/flow.h b/include/net/flow.h
index 7f0adda3bf2fed28c53352d9021574b5eade2738..335bbc52171c10eb4b4b7e03a18eb8147902c6ac 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -40,8 +40,8 @@ struct flowi_common {
 #define FLOWI_FLAG_KNOWN_NH		0x02
 	__u32	flowic_secid;
 	kuid_t  flowic_uid;
-	struct flowi_tunnel flowic_tun_key;
 	__u32		flowic_multipath_hash;
+	struct flowi_tunnel flowic_tun_key;
 };
 
 union flowi_uli {
-- 
2.42.0.758.gaed0368e0e-goog