[PATCH 3.16 150/202] net/packet: fix 4gb buffer limit due to overflow check

[Ben Hutchings]

3.16.66-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Kal Conley <kal.conley@xxxxxxxxxxx>

commit fc62814d690cf62189854464f4bd07457d5e9e50 upstream.

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@xxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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
@@ -3915,7 +3915,7 @@ 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))