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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.

Signed-off-by: Andrey Konovalov <>
Acked-by: Eric Dumazet <>
Signed-off-by: David S. Miller <>
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xairy authored and davem330 committed Mar 30, 2017
1 parent 8f1f7ee commit 2b6867c2ce76c596676bec7d2d525af525fdc6e2
Showing 1 changed file with 2 additions and 2 deletions.
@@ -4193,8 +4193,8 @@ 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 <=
goto out;
if (unlikely(req->tp_frame_size < po->tp_hdrlen +

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