Subject: Re: [PATCH bpf] xsk: Free skb when TX metadata options are invalid

From: Stanislav Fomichev <[email-masked]>
Date: Thu, 14 Nov 2024 10:39:56 -0800

On 11/14, Felix Maurer wrote:
> When a new skb is allocated for transmitting an xsk descriptor, i.e., for
> every non-multibuf descriptor or the first frag of a multibuf descriptor,
> but the descriptor is later found to have invalid options set for the TX
> metadata, the new skb is never freed. This can leak skbs until the send
> buffer is full which makes sending more packets impossible.
> 
> Fix this by freeing the skb in the error path if we are currently dealing
> with the first frag, i.e., an skb allocated in this iteration of
> xsk_build_skb.
> 
> Fixes: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support")
> Reported-by: Michal Schmidt <[email-masked]>
> Signed-off-by: Felix Maurer <[email-masked]>
> ---

Acked-by: Stanislav Fomichev <[email-masked]>

Reminds me of the following:
https://lore.kernel.org/netdev/[email-masked]/#t

Maybe I need to try to cleanup this path. Too many corner cases so it's
impossible to get right :-(