netdev - [RFC PATCH] udp: don't rereference dst

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Message-Id: <1362695800-8633-2-git-send-email-tparkin@katalix.com>
Date:	Thu,  7 Mar 2013 22:36:40 +0000
From:	Tom Parkin <tparkin@...alix.com>
To:	netdev@...r.kernel.org
Cc:	Tom Parkin <tparkin@...alix.com>
Subject: [RFC PATCH] udp: don't rereference dst_entry dev pointer on rcv

When a fragmented IP packet is queued during device teardown, it is possible
for the reassembled packet to hit the UDP rcv path with a NULL dst_entry dev
pointer.  Drop such packets to prevent an oops.
---
 net/ipv4/udp.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 0a073a2..c38a4b1 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1700,6 +1700,9 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 		return __udp4_lib_mcast_deliver(net, skb, uh,
 				saddr, daddr, udptable);
 
+	if (skb_dst(skb)->dev == NULL)
+		goto drop;
+
 	sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 
 	if (sk != NULL) {
-- 
1.7.9.5

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