From: WANG Cong <xiyou.wangcong@gmail.com>
Date: Tue, 10 Mar 2015 00:03:40 +0000 (-0700)
Subject: net_sched: fix struct tc_u_hnode layout in u32
X-Git-Tag: v4.0-rc5~26^2~35
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=5778d39d070b4ac5f889928175b7f2d53ae7504e;p=cascardo%2Flinux.git

net_sched: fix struct tc_u_hnode layout in u32

We dynamically allocate divisor+1 entries for ->ht[] in tc_u_hnode:

  ht = kzalloc(sizeof(*ht) + divisor*sizeof(void *), GFP_KERNEL);

So ->ht is supposed to be the last field of this struct, however
this is broken, since an rcu head is appended after it.

Fixes: 1ce87720d456 ("net: sched: make cls_u32 lockless")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 09487afbfd51..95fdf4e40051 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -78,8 +78,11 @@ struct tc_u_hnode {
 	struct tc_u_common	*tp_c;
 	int			refcnt;
 	unsigned int		divisor;
-	struct tc_u_knode __rcu	*ht[1];
 	struct rcu_head		rcu;
+	/* The 'ht' field MUST be the last field in structure to allow for
+	 * more entries allocated at end of structure.
+	 */
+	struct tc_u_knode __rcu	*ht[1];
 };
 
 struct tc_u_common {