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

commit 2b6867c2ce76c596676bec7d2d525af525fdc6e2 upstream.

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.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8bb77e03a5c2b075a50fb71b5245df6d35a83c19..4a477a5ae92c35677f8ab9e5220b0e8b1a6be0b3 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3672,8 +3672,8 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
                if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))
                        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))