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xdp: fix possible cq entry leak

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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: 35fcde7f8d ("xsk: support for Tx")
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Tested-by: William Tu <u9012063@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Ilya Maximets 2019-07-04 17:25:03 +03:00 committed by Daniel Borkmann
parent 36db2a94f1
commit 675716400d
1 changed files with 4 additions and 7 deletions
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11
net/xdp/xsk.c
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@ -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;
}