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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kal Conley <kal.conley@dectris.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.20 128/183] net/packet: fix 4gb buffer limit due to overflow check
Date:   Mon, 25 Feb 2019 22:11:41 +0100
Message-Id: <20190225195116.295887209@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kal Conley <kal.conley@dectris.com>

[ Upstream commit fc62814d690cf62189854464f4bd07457d5e9e50 ]

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@dectris.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/packet/af_packet.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4292,7 +4292,7 @@ static int packet_set_ring(struct sock *
 		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))