From: Andrey Konovalov <andreyknvl@google.com>
Date: Wed, 29 Mar 2017 14:11:21 +0000 (+0200)
Subject: net/packet: fix overflow in check for tp_frame_nr
X-Git-Url: https://git.stricted.de/?p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git;a=commitdiff_plain;h=492980ca268c3a213a71f5c0aef116b58c665e16;ds=sidebyside

net/packet: fix overflow in check for tp_frame_nr

commit 8f8d28e4d6d815a391285e121c3a53a0b6cb9e7b upstream.

When calculating rb->frames_per_block * req->tp_block_nr the result
can overflow.

Add a check that tp_block_size * tp_block_nr <= UINT_MAX.

Since frames_per_block <= tp_block_size, the expression would
never overflow.

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>
---

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 4a477a5ae92c..cea85d8de1d8 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3684,6 +3684,8 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 		rb->frames_per_block = req->tp_block_size/req->tp_frame_size;
 		if (unlikely(rb->frames_per_block <= 0))
 			goto out;
+		if (unlikely(req->tp_block_size > UINT_MAX / req->tp_block_nr))
+			goto out;
 		if (unlikely((rb->frames_per_block * req->tp_block_nr) !=
 					req->tp_frame_nr))
 			goto out;