UPSTREAM: net/packet: fix overflow in check for priv area size

Subtracting tp_sizeof_priv from tp_block_size and casting to int
to check whether one is less then the other doesn't always work
(both of them are unsigned ints).

Compare them as is instead.

Also cast tp_sizeof_priv to u64 before using BLK_PLUS_PRIV, as
it can overflow inside BLK_PLUS_PRIV otherwise.

Bug: 36725304
Upstream commit: 2b6867c2ce76c596676bec7d2d525af525fdc6e2
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Change-Id: I46bfbaf5f4a5d80f10ddce731a3030f191de4b28

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 3975ac8..d768001 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4138,8 +4138,8 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
                if (unlikely(!PAGE_ALIGNED(req->tp_block_size)))
                        goto out;
                if (po->tp_version >= TPACKET_V3 &&
-                   (int)(req->tp_block_size -
-                         BLK_PLUS_PRIV(req_u->req3.tp_sizeof_priv)) <= 0)
+                   req->tp_block_size <=
+                         BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv))
                        goto out;
                if (unlikely(req->tp_frame_size < po->tp_hdrlen +
                                        po->tp_reserve))