netdev - [PATCH v2] net/packet: fix 4gb buffer limit due to overflow check

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Message-Id: <20190210085712.31622-1-kal.conley@dectris.com>
Date:   Sun, 10 Feb 2019 09:57:11 +0100
From:   Kal Conley <kal.conley@...tris.com>
To:     davem@...emloft.net
Cc:     kal.conley@...tris.com, Willem de Bruijn <willemb@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        Li RongQing <lirongqing@...du.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] net/packet: fix 4gb buffer limit due to overflow check

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.

Fixes: 8f8d28e4d6d8 ("net/packet: fix overflow in check for tp_frame_nr")
Signed-off-by: Kal Conley <kal.conley@...tris.com>
---
Changes in v2:
- Add Signed-off-by and Fixes tag

 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 3b1a78906bc0..1cd1d83a4be0 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4292,7 +4292,7 @@ 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