Re: [PATCH] af_unix: Silence randstruct GCC plugin warning

[Jakub Kicinski]

On Tue, 10 May 2022 17:01:09 -0700 Kees Cook wrote:
> While preparing for Clang randstruct support (which duplicated many of
> the warnings the randstruct GCC plugin warned about), one strange one
> remained only for the randstruct GCC plugin. Eliminating this rids
> the plugin of the last exception.
> 
> It seems the plugin is happy to dereference individual members of
> a cross-struct cast, but it is upset about casting to a whole object
> pointer. This only manifests in one place in the kernel, so just replace
> the variable with individual member accesses. There is no change in
> executable instruction output.
> 
> Drop the last exception from the randstruct GCC plugin.
> 
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Cc: linux-hardening@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> If someone can Ack this, I can carry it in the gcc-plugins tree,
> as I'm trying to remove all its exceptions so I can drop that code.

Acked-by: Jakub Kicinski <kuba@xxxxxxxxxx>