Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Kal Conley <kal.conley@dectris.com>
To:     davem@davemloft.net
Cc:     kal.conley@dectris.com, Willem de Bruijn <willemb@google.com>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Alexander Duyck <alexander.h.duyck@intel.com>,
        Kirill Tkhai <ktkhai@virtuozzo.com>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        Li RongQing <lirongqing@baidu.com>,
        Magnus Karlsson <magnus.karlsson@intel.com>,
        netdev@vger.kernel.org (open list:NETWORKING [GENERAL]),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] net/packet: fix 4gb buffer limit due to overflow check
Date:   Sat,  9 Feb 2019 21:37:00 +0100
Message-Id: <20190209203701.27252-1-kal.conley@dectris.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When calculating rb->frames_per_block * req->tp_block_nr the result
can overflow. Check it for overflow without limiting the total buffer
size to UINT_MAX.

This change fixes support for packet ring buffers >= UINT_MAX.
---
 net/packet/af_packet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d0945253f43b..d603a430378e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4291,7 +4291,7 @@ 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))
+		if (unlikely(rb->frames_per_block > UINT_MAX / req->tp_block_nr))
 			goto out;
 		if (unlikely((rb->frames_per_block * req->tp_block_nr) !=
 					req->tp_frame_nr))
-- 
2.20.1