Re: [PATCH] vti6: Add pmtu handling to vti6_xmit.

[Steffen Klassert <steffen.klassert@secunet.com>]

On Wed, Feb 24, 2016 at 09:37:39PM +0000, Mark McKinstry wrote:
> On 19/02/16 01:19, Steffen Klassert wrote:
> > On Thu, Feb 18, 2016 at 01:40:00AM +0000, Mark McKinstry wrote:
> >> This patch fixes our issue, thanks. In our scenario the tunnel path MTU
> >> now gets updated so that subsequent large packets sent over the tunnel
> >> get fragmented correctly.
> > I've applied this patch to the ipsec tree now.
> > Thanks for testing!
> I spoke too soon. Upon further testing with this patch we have found it 
> causes
> a skt buffer leak. This is problematic for us and can cause memory 
> exhaustion in
> one of our test scenarios that has an IPv4 IPsec tunnel over a PPP link. 

The patch below is what I plan to apply on top of the original patch.

Subject: [PATCH] vti: Fix recource leeks on pmtu discovery

A recent patch introduced pmtu handling directly in the
vti transmit routine. Unfortunately we now return without
releasing the dst_entry and freeing the sk_buff. This patch
fixes the issue.

Fixes: 325b71fe0f57 ("vti: Add pmtu handling to vti_xmit.")
Reported-by: Mark McKinstry <Mark.McKinstry@alliedtelesis.co.nz>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv4/ip_vti.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 6862305..2ea2b6e 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -206,7 +206,8 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
 		else
 			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 
-		return -EMSGSIZE;
+		dst_release(dst);
+		goto tx_error;
 	}
 
 	err = dst_output(tunnel->net, skb->sk, skb);
-- 
1.9.1