Commit 7a230cfd authored by Eric Dumazet's avatar Eric Dumazet Committed by Sasha Levin

netem: fix skb_orphan_partial()

[ Upstream commit f6ba8d33 ]

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: f2f872f9 ("netem: Introduce skb_orphan_partial() helper")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarMichael Madsen <mkm@nabto.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 8404b686
...@@ -1641,17 +1641,17 @@ EXPORT_SYMBOL(sock_wfree); ...@@ -1641,17 +1641,17 @@ EXPORT_SYMBOL(sock_wfree);
void skb_orphan_partial(struct sk_buff *skb) void skb_orphan_partial(struct sk_buff *skb)
{ {
/* 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 if (skb->destructor == sock_wfree
#ifdef CONFIG_INET #ifdef CONFIG_INET
|| skb->destructor == tcp_wfree || skb->destructor == tcp_wfree
#endif #endif
) { ) {
atomic_sub(skb->truesize - 1, &skb->sk->sk_wmem_alloc); struct sock *sk = skb->sk;
skb->truesize = 1;
if (atomic_inc_not_zero(&sk->sk_refcnt)) {
atomic_sub(skb->truesize, &sk->sk_wmem_alloc);
skb->destructor = sock_efree;
}
} else { } else {
skb_orphan(skb); skb_orphan(skb);
} }
......
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