Re: [PATCH net] tun: free page on build_skb failure in tun_xdp_one()

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Weiming Shi wrote:
> When build_skb() fails in tun_xdp_one(), the function sets ret to
> -ENOMEM and jumps to the out label, which returns without freeing the
> page that vhost_net_build_xdp() allocated for the frame. As with the
> short-frame rejection path, tun_sendmsg() discards the per-buffer error
> and still returns total_len, so vhost_tx_batch() takes the success path
> and never frees the page. Each build_skb() failure in a batch leaks one
> page-frag chunk.
> 
> Free the page before taking the error path, matching the put_page() the
> other error exits of tun_xdp_one() already perform.
> 
> Fixes: 043d222f93ab ("tuntap: accept an array of XDP buffs through sendmsg()")
> Reported-by: Xiang Mei <xmei5@asu.edu>
> Assisted-by: Claude:claude-opus-4-7
> Signed-off-by: Weiming Shi <bestswngs@gmail.com>

Reviewed-by: Willem de Bruijn <willemb@google.com>