[PATCH 3.10 248/268] net/packet: fix overflow in check for tp_frame_nr

Willy Tarreau
2017-06-19T19:10:51Z

From: Andrey Konovalov <andreyknvl@google.com>

commit 8f8d28e4d6d815a391285e121c3a53a0b6cb9e7b upstream.

When calculating rb->frames_per_block * req->tp_block_nr the result
can overflow.

Add a check that tp_block_size * tp_block_nr <= UINT_MAX.

Since frames_per_block <= tp_block_size, the expression would
never overflow.

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>
---
net/packet/af_packet.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 4a477a5..cea85d8 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3684,6 +3684,8 @@ 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))
+ goto out;
if (unlikely((rb->frames_per_block * req->tp_block_nr) !=
req->tp_frame_nr))
goto out;
--
2.8.0.rc2.1.gbe9624a