netdev - [net 1/1] tipc: eliminate access after delete in group_filter

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Date:   Mon, 27 Nov 2017 20:13:39 +0100
From:   Jon Maloy <jon.maloy@...csson.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     <mohan.krishna.ghanta.krishnamurthy@...csson.com>,
        <tung.q.nguyen@...tech.com.au>, <hoang.h.le@...tech.com.au>,
        <jon.maloy@...csson.com>, <canh.d.luu@...tech.com.au>,
        <ying.xue@...driver.com>, <tipc-discussion@...ts.sourceforge.net>
Subject: [net  1/1] tipc: eliminate access after delete in group_filter_msg()

KASAN revealed another access after delete in group.c. This time
it found that we read the header of a received message after the
buffer has been released.

Signed-off-by: Jon Maloy <jon.maloy@...csson.com>
---
 net/tipc/group.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tipc/group.c b/net/tipc/group.c
index 12777ca..95fec2c 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -497,6 +497,7 @@ void tipc_group_filter_msg(struct tipc_group *grp, struct sk_buff_head *inputq,
 	while ((skb = skb_peek(defq))) {
 		hdr = buf_msg(skb);
 		mtyp = msg_type(hdr);
+		blks = msg_blocks(hdr);
 		deliver = true;
 		ack = false;
 		update = false;
@@ -546,7 +547,6 @@ void tipc_group_filter_msg(struct tipc_group *grp, struct sk_buff_head *inputq,
 		if (!update)
 			continue;
 
-		blks = msg_blocks(hdr);
 		tipc_group_update_rcv_win(grp, blks, node, port, xmitq);
 	}
 	return;
-- 
2.1.4