Subject: Re: [PATCH bpf-next v2 01/15] net: Preserve metadata on pskb_expand_head

From: Jakub Kicinski <[email-masked]>
Date: Thu, 23 Oct 2025 17:51:19 -0700

On Sun, 19 Oct 2025 14:45:25 +0200 Jakub Sitnicki wrote:
> pskb_expand_head() copies headroom, including skb metadata, into the newly
> allocated head, but then clears the metadata. As a result, metadata is lost
> when BPF helpers trigger an skb head reallocation.

True, then again if someone is reallocating headroom they may very well
push a header after, shifting metadata into an uninitialized part of
the headroom. Not sure we can do much about that, but perhaps worth
being more explicit in the commit msg?