linux-kernel - [PATCH 3.10 248/268] net/packet: fix overflow in check for tp_frame

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Message-Id: <1497897167-14556-249-git-send-email-w@1wt.eu>
Date:   Mon, 19 Jun 2017 20:32:27 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Andrey Konovalov <andreyknvl@...gle.com>,
        "David S . Miller" <davem@...emloft.net>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 248/268] net/packet: fix overflow in check for tp_frame_nr

From: Andrey Konovalov <andreyknvl@...gle.com>

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@...gle.com>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Willy Tarreau <w@....eu>
---
 net/packet/af_packet.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 4a477a5..cea85d8 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;
-- 
2.8.0.rc2.1.gbe9624a