From 675716400da6f15b9d3db04ef74ee74ca9a00af3 Mon Sep 17 00:00:00 2001 From: Ilya Maximets Date: Thu, 4 Jul 2019 17:25:03 +0300 Subject: [PATCH] xdp: fix possible cq entry leak MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Completion queue address reservation could not be undone. In case of bad 'queue_id' or skb allocation failure, reserved entry will be leaked reducing the total capacity of completion queue. Fix that by moving reservation to the point where failure is not possible. Additionally, 'queue_id' checking moved out from the loop since there is no point to check it there. Fixes: 35fcde7f8deb ("xsk: support for Tx") Signed-off-by: Ilya Maximets Acked-by: Björn Töpel Tested-by: William Tu Signed-off-by: Daniel Borkmann --- net/xdp/xsk.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index d4d6f10..b994c32 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -240,6 +240,9 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, mutex_lock(&xs->mutex); + if (xs->queue_id >= xs->dev->real_num_tx_queues) + goto out; + while (xskq_peek_desc(xs->tx, &desc)) { char *buffer; u64 addr; @@ -250,12 +253,6 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, goto out; } - if (xskq_reserve_addr(xs->umem->cq)) - goto out; - - if (xs->queue_id >= xs->dev->real_num_tx_queues) - goto out; - len = desc.len; skb = sock_alloc_send_skb(sk, len, 1, &err); if (unlikely(!skb)) { @@ -267,7 +264,7 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, addr = desc.addr; buffer = xdp_umem_get_data(xs->umem, addr); err = skb_store_bits(skb, 0, buffer, len); - if (unlikely(err)) { + if (unlikely(err) || xskq_reserve_addr(xs->umem->cq)) { kfree_skb(skb); goto out; } -- 2.7.4