Re: [PATCH] genetlink: free the skb on 'group >= family->n_mcgrps'

[Eric Dumazet]

On Mon, May 4, 2026 at 2:17 AM Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:
>
> These methods generally consume ownership of the provided skb, so even
> if an error path is encountered, the skb is freed. This is because the
> very first thing they do after some initial setup is to unconditionally
> consume the skb via consume_skb(skb). Any subsequent errors lead to the
> core netlink layer freeing the skb.
>
> However, there is one check that occurs before ownership is passed,
> which is the check for the group index. So if this error condition is
> encountered, then the skb is leaked. This error condition is generally
> considered a violation of the netlink API, so it's not expected to occur
> under normal circumstances. For the same reason, no callers check for
> this error condition, and no callers need to be adjusted. However, we
> should still follow the same ownership semantics of the rest of the
> function. Thus, free the skb in this codepath.
>
> Assisted-by: Antigravity:gemini
> Suggested-by: Andrew Lunn <andrew@xxxxxxx>
> Suggested-by: Matthew Maurer <mmaurer@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/845b36ba-7b3a-41f2-acb2-b284f253e2ca@xxxxxxx
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>

1) This looks like a fix meant for net tree ?

2) We require a Fixes: tag for bug fixes.

For more details I highly recommend reading at least the tl;dr part of:

Documentation/process/maintainer-netdev.rst

Thank you.