[PATCH 3.2 080/101] net/packet: fix overflow in check for tp_frame_nr

From	Ben Hutchings <ben@decadent.org.uk>
Newsgroups	linux.kernel
Subject	[PATCH 3.2 080/101] net/packet: fix overflow in check for tp_frame_nr
Date	2017-06-01 18:50 +0200
Message-ID	<tNBsn-53m-69@gated-at.bofh.it> (permalink)
References	<tNAwh-4oP-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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

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

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: Ben Hutchings <ben@decadent.org.uk>
---
 net/packet/af_packet.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3649,6 +3649,8 @@ 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))
+			goto out;
 		if (unlikely((rb->frames_per_block * req->tp_block_nr) !=
 					req->tp_frame_nr))
 			goto out;

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[PATCH 3.2 080/101] net/packet: fix overflow in check for tp_frame_nr Ben Hutchings <ben@decadent.org.uk> - 2017-06-01 18:50 +0200

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