Subject: Re: [PATCH net] tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()

From: Jakub Kicinski <[email-masked]>
Date: Mon, 25 May 2026 11:54:49 -0700

On Mon, 25 May 2026 11:41:59 -0700 Eric Dumazet wrote:
> > Are we okay with what sashiko is reporting?
> > If it's legit it may be better to fix in one series  
> 
> Maybe, but iptunnel_pmtud_check_icmpv6() is also calling
> pskb_may_pull(), and always had.
> 
> Perhaps it is time for CONFIG_DEBUG_NET kernels to always reallocate
> skb->head at every pskb_may_pull() call, just to expose these bugs.

Ack, but callers may ensure pulling just the ip header is already safe
at this point vs pulling an extra L4 hdr.

> I fear that a series will never be complete, sashiko will keep finding issues.
> 
> I can try a V2, but will probably give up soon.

Thanks, let's try v2. If it turns into a rabbit hole we can just apply
v1, LMK.