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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Yotam Gigi <yotamg@mellanox.com>,
        Jiri Pirko <jiri@mellanox.com>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 22/69] net/sched: fix ->get helper of the matchall cls
Date:   Mon, 15 Apr 2019 20:58:40 +0200
Message-Id: <20190415183730.445550198@linuxfoundation.org>
In-Reply-To: <20190415183726.036654568@linuxfoundation.org>
References: <20190415183726.036654568@linuxfoundation.org>
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From: Nicolas Dichtel <nicolas.dichtel@6wind.com>

[ Upstream commit 0db6f8befc32c68bb13d7ffbb2e563c79e913e13 ]

It returned always NULL, thus it was never possible to get the filter.

Example:
$ ip link add foo type dummy
$ ip link add bar type dummy
$ tc qdisc add dev foo clsact
$ tc filter add dev foo protocol all pref 1 ingress handle 1234 \
	matchall action mirred ingress mirror dev bar

Before the patch:
$ tc filter get dev foo protocol all pref 1 ingress handle 1234 matchall
Error: Specified filter handle not found.
We have an error talking to the kernel

After:
$ tc filter get dev foo protocol all pref 1 ingress handle 1234 matchall
filter ingress protocol all pref 1 matchall chain 0 handle 0x4d2
  not_in_hw
        action order 1: mirred (Ingress Mirror to device bar) pipe
        index 1 ref 1 bind 1

CC: Yotam Gigi <yotamg@mellanox.com>
CC: Jiri Pirko <jiri@mellanox.com>
Fixes: fd62d9f5c575 ("net/sched: matchall: Fix configuration race")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/cls_matchall.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/net/sched/cls_matchall.c
+++ b/net/sched/cls_matchall.c
@@ -125,6 +125,11 @@ static void mall_destroy(struct tcf_prot
 
 static void *mall_get(struct tcf_proto *tp, u32 handle)
 {
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+
+	if (head && head->handle == handle)
+		return head;
+
 	return NULL;
 }