diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-05-11 15:24:41 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-05-11 21:32:48 -0400 |
| commit | f6ba8d33cfbb46df569972e64dbb5bb7e929bfd9 (patch) | |
| tree | a341e4360d881c74496da6f86d7127a9ffe65191 /net | |
| parent | 4e3c60ed2f594e4ec6bb81d71ef6993e60f740d8 (diff) | |
netem: fix skb_orphan_partial()
I should have known that lowering skb->truesize was dangerous :/
In case packets are not leaving the host via a standard Ethernet device,
but looped back to local sockets, bad things can happen, as reported
by Michael Madsen ( https://bugzilla.kernel.org/show_bug.cgi?id=195713 )
So instead of tweaking skb->truesize, lets change skb->destructor
and keep a reference on the owner socket via its sk_refcnt.
Fixes: f2f872f9272a ("netem: Introduce skb_orphan_partial() helper")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Michael Madsen <mkm@nabto.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/sock.c | 20 |
1 files changed, 8 insertions, 12 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 79c6aee6af9b..e43e71d7856b 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1803,28 +1803,24 @@ EXPORT_SYMBOL(skb_set_owner_w); * delay queue. We want to allow the owner socket to send more * packets, as if they were already TX completed by a typical driver. * But we also want to keep skb->sk set because some packet schedulers - * rely on it (sch_fq for example). So we set skb->truesize to a small - * amount (1) and decrease sk_wmem_alloc accordingly. + * rely on it (sch_fq for example). */ void skb_orphan_partial(struct sk_buff *skb) { - /* If this skb is a TCP pure ACK or already went here, - * we have nothing to do. 2 is already a very small truesize. - */ - if (skb->truesize <= 2) + if (skb_is_tcp_pure_ack(skb)) return; - /* TCP stack sets skb->ooo_okay based on sk_wmem_alloc, - * so we do not completely orphan skb, but transfert all - * accounted bytes but one, to avoid unexpected reorders. - */ if (skb->destructor == sock_wfree #ifdef CONFIG_INET || skb->destructor == tcp_wfree #endif ) { - atomic_sub(skb->truesize - 1, &skb->sk->sk_wmem_alloc); - skb->truesize = 1; + struct sock *sk = skb->sk; + + if (atomic_inc_not_zero(&sk->sk_refcnt)) { + atomic_sub(skb->truesize, &sk->sk_wmem_alloc); + skb->destructor = sock_efree; + } } else { skb_orphan(skb); } |