From: Andrey Konovalov <andreyknvl@google.com>
Date: Wed, 29 Mar 2017 14:11:20 +0000 (+0200)
Subject: net/packet: fix overflow in check for priv area size
X-Git-Tag: v3.2.89~23
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=091a6de006536c50f8a30db60d994a5b083b1c7b

net/packet: fix overflow in check for priv area size

commit 2b6867c2ce76c596676bec7d2d525af525fdc6e2 upstream.

Subtracting tp_sizeof_priv from tp_block_size and casting to int
to check whether one is less then the other doesn't always work
(both of them are unsigned ints).

Compare them as is instead.

Also cast tp_sizeof_priv to u64 before using BLK_PLUS_PRIV, as
it can overflow inside BLK_PLUS_PRIV otherwise.

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: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2235fe5bb886..3a5a58f8baa2 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3637,8 +3637,8 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 		if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))
 			goto out;
 		if (po->tp_version >= TPACKET_V3 &&
-		    (int)(req->tp_block_size -
-			  BLK_PLUS_PRIV(req_u->req3.tp_sizeof_priv)) <= 0)
+		    req->tp_block_size <=
+			  BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv))
 			goto out;
 		if (unlikely(req->tp_frame_size < po->tp_hdrlen +
 					po->tp_reserve))