Re: [PATCH v2 1/2] net: Fix skb_segment when splitting gso_size mangled skb having linear-headed frag_list whose head_frag=true

I must admit I more than a bit lost in the many turns of skb_segment(),
but the above does not look like the correct solution, as it will make
the later BUG_ON() unreachable/meaningless.

Sorry, the subsequent BUG_ON maybe should be removed in this patch, because
for skb_headlen(list_skb) > len, it will continue splitting as commit 13acc94eff122 
(net: permit skb_segment on head_frag frag_list skb) does.

Do I read correctly that when the BUG_ON() triggers:

list_skb->len is 125
len is 75
list_skb->frag_head is true

yes, it's correct.
list_skb->len is 125
gso_size is 75, also the len in the BUG_ON conditon
list_skb->head_frag is true
 

It looks like skb_segment() is becoming even and ever more complex to
cope with unexpected skb layouts, only possibly when skb_segment() is
called by some BPF helpers.

Thanks,

Paolo

I'll wait for more suggestions from others.

Thanks

Fred Li