net/packet: fix overflow in check for tp_reserve

net/packet: fix overflow in check for tp_reserve

commit bcc5364bdcfe131e6379363f089e7b4108d35b70 upstream.

When calculating po->tp_hdrlen + po->tp_reserve the result can overflow.

Fix by checking that tp_reserve <= INT_MAX on assign.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
[sw0312.kim: cherry-pick from linux-3.10.y to fix CVE-2017-7308]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I7654b253882584ad30f5dbd38dcf315446e98a48