pkt_sched: cls_u32: Fix locking in u32_change()

[ Upstream commit: 6f57321422e0d359e83c978c2b03db77b967b7d5 ]

New nodes are inserted in u32_change() under rtnl_lock() with wmb(),
so without tcf_tree_lock() like in other classifiers (e.g. cls_fw).
This isn't enough without rmb() on the read side, but on the other
hand adding such barriers doesn't give any savings, so the lock is
added instead.

Reported-by: m0sia <m0sia@plotinka.ru>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 246f9065ce34b0ad8f7b176807dea7d50221b087..ea51fcd2ac8e26560035d5e38963122c37c931d5 100644 (file)
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -637,8 +637,9 @@ static int u32_change(struct tcf_proto *tp, unsigned long base, u32 handle,
                                break;
 
                n->next = *ins;
-               wmb();
+               tcf_tree_lock(tp);
                *ins = n;
+               tcf_tree_unlock(tp);
 
                *arg = (unsigned long)n;
                return 0;