Subject: Re: [PATCH net v2] virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false

From: Jakub Kicinski <[email-masked]>
Date: Sat, 14 Mar 2026 18:12:43 -0700

On Sat, 14 Mar 2026 21:11:33 +0100 Eric Dumazet wrote:
> > On Thu, 12 Mar 2026 10:54:06 +0800 xietangxin wrote:  
> > > Fixes: f2fc6a54585a ("[NETNS][IPV6] route6 - move ip6_dst_ops inside the network namespace")
> > > Cc: [email-masked]
> > > Signed-off-by: xietangxin <[email-masked]>  
> >
> > The Fixes tag should be:
> >
> > Fixes: 0287587884b1 ("net: better IFF_XMIT_DST_RELEASE support")  
> 
> I disagree
> 
> What was the situation before this patch ?

My thinking process was that it's fairly unusual that the dst is kept
because the stack decided so. Normally its the device driver that asks
for dst to be kept when its xmit is called. I thought 0287587884b1 was
the first time when stack could make the dst decision behind device
driver's back. But my analysis was very shallow, could well be wrong.