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From dd07486ceba48b5d2157b212bb9bd5ce9a46b593 Mon Sep 17 00:00:00 2001
From: Andrey Konovalov <andreyknvl@google.com>
Date: Wed, 29 Mar 2017 16:11:20 +0200
Subject: [PATCH] net/packet: fix overflow in check for priv area size
[ Upstream commit 2b6867c2ce76c596676bec7d2d525af525fdc6e2 ]
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.
CVE: CVE-2017-7308
Upstream-Status: Backport
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: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
---
net/packet/af_packet.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b9d1baa..83c05aa 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3867,8 +3867,8 @@ 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))
--
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