From: Roland Dreier <roland@purestorage.com>
Date: Mon, 31 Jan 2011 21:16:00 +0000 (-0800)
Subject: net: Add default_mtu() methods to blackhole dst_ops
X-Git-Tag: v2.6.38-rc4~15^2~35
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ec831ea72ee5d7d473899e27a86bd659482c4d0d;p=pandora-kernel.git

net: Add default_mtu() methods to blackhole dst_ops

When an IPSEC SA is still being set up, __xfrm_lookup() will return
-EREMOTE and so ip_route_output_flow() will return a blackhole route.
This can happen in a sndmsg call, and after d33e455337ea ("net: Abstract
default MTU metric calculation behind an accessor.") this leads to a
crash in ip_append_data() because the blackhole dst_ops have no
default_mtu() method and so dst_mtu() calls a NULL pointer.

Fix this by adding default_mtu() methods (that simply return 0, matching
the old behavior) to the blackhole dst_ops.

The IPv4 part of this patch fixes a crash that I saw when using an IPSEC
VPN; the IPv6 part is untested because I don't have an IPv6 VPN, but it
looks to be needed as well.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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