netdev - Re: kernels > v4.12 oops/crash with ipsec-traffic: bisected to b838d5e1c5b6e57b10ec8af2268824041e3ea911: ipv4: mark DST_NOGC and remove the operation of dst

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Date:   Wed, 12 Sep 2018 10:50:46 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Tobias Hommel <netdev-list@...oetigt.de>
CC:     Wolfgang Walter <linux@...m.de>,
        Kristian Evensen <kristian.evensen@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        <weiwan@...gle.com>, <edumazet@...gle.com>
Subject: Re: kernels > v4.12 oops/crash with ipsec-traffic: bisected to
 b838d5e1c5b6e57b10ec8af2268824041e3ea911: ipv4: mark DST_NOGC and remove the
 operation of dst_free()

On Tue, Sep 11, 2018 at 09:02:48PM +0200, Tobias Hommel wrote:
> > > Subject: [PATCH RFC] xfrm: Fix NULL pointer dereference when skb_dst_force
> > > clears the dst_entry.
> > > 
> > > Since commit 222d7dbd258d ("net: prevent dst uses after free")
> > > skb_dst_force() might clear the dst_entry attached to the skb.
> > > The xfrm code don't expect this to happen, so we crash with
> > > a NULL pointer dereference in this case. Fix it by checking
> > > skb_dst(skb) for NULL after skb_dst_force() and drop the packet
> > > in cast the dst_entry was cleared.
> > > 
> > > Fixes: 222d7dbd258d ("net: prevent dst uses after free")
> > > Reported-by: Tobias Hommel <netdev-list@...oetigt.de>
> > > Reported-by: Kristian Evensen <kristian.evensen@...il.com>
> > > Reported-by: Wolfgang Walter <linux@...m.de>
> > > Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
> > > ---
> > 
> > This patch fixes the problem here.
> > 
> > XfrmFwdHdrError gets around 80 at the very beginning and remains so. Probably 
> > this happens when some route are changed/set then. 
> > 
> > Regards and thanks,
> 
> Same here, we're now running stable for ~6 hours, XfrmFwdHdrError is at 220.
> This is less than 1 lost packet per minute, which seems to be okay for now.

Thanks a lot for testing! This is now applied to the ipsec tree.