Re: [PATCH] ipv6: fix NULL pointer dereference in ip6_output()

On Wed, Dec 08, 2021 at 08:46:37AM -0700, David Ahern wrote:

On 12/8/21 3:51 AM, Florian Westphal wrote:

quoted

David Ahern [off-list ref] wrote:

quoted

On 12/7/21 5:21 PM, Andrea Mayer wrote:

quoted

+        IP6CB(skb)->iif = skb->skb_iif;
         [...]

What do you think?

I like that approach over the need for a fall back in core ipv6 code.

What if the device is removed after ->iif assignment and before dev lookup?

good point. SR6 should make sure the iif is not cleared, and the
fallback to the skb->dev is still needed in case of delete.

Thanks for the explanation. I was thinking that ->iif can safely be
assumed to be valid. Florian's point that device can be removed is a
good one. My bad for not putting the check and thanks for fixing.