linux-kernel - Re: [PATCH net-next 06/11] tools: ynl-gen: don't validate nested array attribute types

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Message-ID: <20250905172334.0411e05e@kernel.org>
Date: Fri, 5 Sep 2025 17:23:34 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Asbjørn Sloth Tønnesen
 <ast@...erby.net>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni
 <pabeni@...hat.com>, Donald Hunter <donald.hunter@...il.com>, Simon Horman
 <horms@...nel.org>, Jacob Keller <jacob.e.keller@...el.com>, Andrew Lunn
 <andrew+netdev@...n.ch>, wireguard@...ts.zx2c4.com, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 06/11] tools: ynl-gen: don't validate nested
 array attribute types

On Thu,  4 Sep 2025 22:01:29 +0000 Asbjørn Sloth Tønnesen wrote:
> In nested arrays don't require that the intermediate
> attribute type should be a valid attribute type, it
> might just be an index or simple 0, it is often not
> even used.
> 
> See include/net/netlink.h about NLA_NESTED_ARRAY:
> > The difference to NLA_NESTED is the structure:
> > NLA_NESTED has the nested attributes directly inside
> > while an array has the nested attributes at another
> > level down and the attribute types directly in the
> > nesting don't matter.  

I don't understand, please provide more details.
This is an ArrayNest, right?

[ARRAY-ATTR]
  [ENTRY]
    [MEMBER1]
    [MEMBER2]
  [ENTRY]
    [MEMBER1]
    [MEMBER2]

Which level are you saying doesn't matter?
If entry is a nest it must be a valid nest.
What the comment you're quoting is saying is that the nla_type of ENTRY
doesn't matter.