net/packet: fix overflow in check for tp_frame_nr

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>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name net-packet-fix-overflow-in-check-for-tp_frame_nr.patch

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8ab0974f4ee2f4a09628872bf3e208bdd7e8d56d..e064e33428256b88befb1b4d3fd5e2d17b436d3a 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4247,6 +4247,8 @@ 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;