Subject: [PATCH 07/23] net/packet: fix 4gb buffer limit due to overflow check

From: Kal Conley <[email-masked]>
Date: Sun, 10 Feb 2019 09:57:11 +0100

[ 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 <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 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