netdev - [PATCH net] ipv6: skip __ipv6_select_ident when there is no skb

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Date:	Wed, 18 Mar 2015 14:52:15 +0100
From:	Sabrina Dubroca <sd@...asysnail.net>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, matt@...tgrant.net.nz,
	Sabrina Dubroca <sd@...asysnail.net>,
	Vladislav Yasevich <vyasevic@...hat.com>
Subject: [PATCH net] ipv6: skip __ipv6_select_ident when there is no skb_dst

Matt Grant reported frequent crashes in ipv6_select_ident when
udp6_ufo_fragment is called from openvswitch on a skb that doesn't
have a dst_entry set.

Skip __ipv6_select_ident in case of a NULL rt.

Fixes: 0508c07f5e0c ("ipv6: Select fragment id during UFO segmentation if not set.")
Cc: Vladislav Yasevich <vyasevic@...hat.com>
Reported-by: Matt Grant <matt@...tgrant.net.nz>
Tested-by: Matt Grant <matt@...tgrant.net.nz>
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
David, can you queue it for stable (3.19)?

 net/ipv6/output_core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 74581f706c4d..52b1bc76d5c5 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -62,12 +62,14 @@ EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
 void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
 {
 	static u32 ip6_idents_hashrnd __read_mostly;
-	u32 id;
+	u32 id = 0;
 
 	net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
 
-	id = __ipv6_select_ident(ip6_idents_hashrnd, &rt->rt6i_dst.addr,
-				 &rt->rt6i_src.addr);
+	if (rt)
+		id = __ipv6_select_ident(ip6_idents_hashrnd, &rt->rt6i_dst.addr,
+					 &rt->rt6i_src.addr);
+
 	fhdr->identification = htonl(id);
 }
 EXPORT_SYMBOL(ipv6_select_ident);
-- 
2.3.3

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