netdev - Re: Followup: Kernel memory leak on 4.11+ & 5.3.x with IPsec

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Date:   Mon, 4 Nov 2019 12:25:37 -0600
From:   JD <jdtxs00@...il.com>
To:     Steffen Klassert <steffen.klassert@...unet.com>
Cc:     netdev@...r.kernel.org, gregkh@...uxfoundation.org
Subject: Re: Followup: Kernel memory leak on 4.11+ & 5.3.x with IPsec

On 11/1/2019 2:53 AM, Steffen Klassert wrote:
> On Wed, Oct 30, 2019 at 02:30:27PM -0500, JD wrote:
>> Here are some clear steps to reproduce:
>> - On your preferred OS, install an IPsec daemon/software
>> (strongswan/openswan/whatever)
>> - Setup a IKEv2 conn in tunnel mode. Use a RFC1918 private range for
>> your client IP pool. e.g: 10.2.0.0/16
>> - Enable IP forwarding (net.ipv4.ip_forward = 1)
>> - MASQUERADE the 10.2.0.0/16 range using iptables, e.g: "-A
>> POSTROUTING -s 10.2.0.0/16 -o eth0 -j MASQUERADE"
>> - Connect some IKEv2 clients (any device, any platform, doesn't
>> matter) and pass traffic through the tunnel.
>> ^^ It speeds up the leak if you have multiple tunnels passing traffic
>> at the same time.
>>
>> - Observe memory is lost over time and never recovered. Doesn't matter
>> if you restart the daemon, bring down the tunnels, or even unload
>> xfrm/ipsec modules. The memory goes into the void. Only way to reclaim
>> is by restarting completely.
>>
>> Please let me know if anything further is needed to diagnose/debug
>> this problem. We're stuck with the 4.9 kernel because all newer
>> kernels leak memory. Any help or advice is appreciated.
> Looks like we forget to free the page that we use for
> skb page fragments when deleting the xfrm_state.
>
> Can you please try the patch below? I don't have access
> to my test environment today, so this patch is untested.
> I'll try to do some tests on Monday.
>
>
> diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
> index c6f3c4a1bd99..f3423562d933 100644
> --- a/net/xfrm/xfrm_state.c
> +++ b/net/xfrm/xfrm_state.c
> @@ -495,6 +495,8 @@ static void ___xfrm_state_destroy(struct xfrm_state *x)
>   		x->type->destructor(x);
>   		xfrm_put_type(x->type);
>   	}
> +	if (x->xfrag.page)
> +		put_page(x->xfrag.page);
>   	xfrm_dev_state_free(x);
>   	security_xfrm_state_free(x);
>   	xfrm_state_free(x);

Hello Steffen,

I left the stress test running over the weekend and everything still 
looks great. Your patch definitely resolves the leak.

Everything kernel 4.11 and above will need this fix afaik. CC'ed Greg 
KH. Will need backporting to 4.14/4.19.

Thanks again for your help and let me know if anything further is needed 
from me.