From 4682a0358639b29cf69437ed909c6221f8c89847 Mon Sep 17 00:00:00 2001
From: David Miller <davem@davemloft.net>
Date: Tue, 16 Dec 2014 17:58:17 -0500
Subject: [PATCH] netlink: Always copy on mmap TX.

Checking the file f_count and the nlk->mapped count is not completely
sufficient to prevent the mmap'd area contents from changing from
under us during netlink mmap sendmsg() operations.

Be careful to sample the header's length field only once, because this
could change from under us as well.

Fixes: 5fd96123ee19 ("netlink: implement memory mapped sendmsg()")
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
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Reading git-format-patch failed