[75/89] macvlan: fix a possible use after free

[Greg KH]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Eric Dumazet <eric.dumazet@xxxxxxxxx>

[ Upstream commit 4ec7ac1203bcf21f5e3d977c9818b1a56c9ef40d ]

Commit bc416d9768 (macvlan: handle fragmented multicast frames) added a
possible use after free in macvlan_handle_frame(), since
ip_check_defrag() uses pskb_may_pull() : skb header can be reallocated.

Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/macvlan.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -172,6 +172,7 @@ static rx_handler_result_t macvlan_handl
 		skb = ip_check_defrag(skb, IP_DEFRAG_MACVLAN);
 		if (!skb)
 			return RX_HANDLER_CONSUMED;
+		eth = eth_hdr(skb);
 		src = macvlan_hash_lookup(port, eth->h_source);
 		if (!src)
 			/* frame comes from an external address */


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