This is a note to let you know that I've just added the patch titled
netem: fix skb_orphan_partial()
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netem-fix-skb_orphan_partial.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f6ba8d33cfbb46df569972e64dbb5bb7e929bfd9 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu, 11 May 2017 15:24:41 -0700
Subject: netem: fix skb_orphan_partial()
From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit f6ba8d33cfbb46df569972e64dbb5bb7e929bfd9 upstream.
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@xxxxxxxxxx>
Reported-by: Michael Madsen <mkm@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/sock.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1633,17 +1633,17 @@ EXPORT_SYMBOL(sock_wfree);
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
#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);
}
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-3.18/netem-fix-skb_orphan_partial.patch