netdev - [Patch net-next] net_sched: check NULL in tcf_block

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Message-Id: <20171103003208.12329-1-xiyou.wangcong@gmail.com>
Date:   Thu,  2 Nov 2017 17:32:08 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     dave.taht@...il.com, Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...lanox.com>
Subject: [Patch net-next] net_sched: check NULL in tcf_block_put()

Callers of tcf_block_put() could pass NULL so
we can't use block->q before checking if block is
NULL or not.

tcf_block_put_ext() callers are fine, it is always
non-NULL.

Fixes: 8c4083b30e56 ("net: sched: add block bind/unbind notif. and extended block_get/put")
Reported-by: Dave Taht <dave.taht@...il.com>
Cc: Jiri Pirko <jiri@...lanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/sched/cls_api.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index a26c690b48ac..ad35bb4dffaa 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -340,9 +340,6 @@ void tcf_block_put_ext(struct tcf_block *block,
 {
 	struct tcf_chain *chain, *tmp;
 
-	if (!block)
-		return;
-
 	tcf_block_offload_unbind(block, q, ei);
 
 	list_for_each_entry_safe(chain, tmp, &block->chain_list, list)
@@ -362,6 +359,8 @@ void tcf_block_put(struct tcf_block *block)
 {
 	struct tcf_block_ext_info ei = {0, };
 
+	if (!block)
+		return;
 	tcf_block_put_ext(block, NULL, block->q, &ei);
 }
 
-- 
2.13.0