linux-kernel - Re: [PATCH] fs/affs: struct slink_front: Replace 1-element array with flexible array

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Message-ID: <202407110901.AB3DEF0A@keescook>
Date: Thu, 11 Jul 2024 09:05:25 -0700
From: Kees Cook <kees@...nel.org>
To: David Sterba <dsterba@...e.cz>
Cc: David Sterba <dsterba@...e.com>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] fs/affs: struct slink_front: Replace 1-element array
 with flexible array

On Thu, Jul 11, 2024 at 04:29:28PM +0200, David Sterba wrote:
> On Wed, Jul 10, 2024 at 03:57:34PM -0700, Kees Cook wrote:
> > Replace the deprecated[1] use of a 1-element array in
> > struct slink_front with a modern flexible array.
> > 
> > No binary differences are present after this conversion.
> > 
> > Link: https://github.com/KSPP/linux/issues/79 [1]
> > Signed-off-by: Kees Cook <kees@...nel.org>
> 
> Thanks, I've added the 3 patches to my tree.

Thanks!

> I've noticed there's one
> more 1-element array in struct affs_root_head (hashtable):
> 
> https://elixir.bootlin.com/linux/latest/source/fs/affs/amigaffs.h#L50
> 
> The struct is used only partially by AFFS_ROOT_HEAD from affs_fill_super
> and not accessing the hashtable. This could have been missed by the
> tools you use or was the conversion intentionally skipped?

Yeah -- this was intentional. We wanted to finish conversion of members
that were actually being used by the kernel. There is a lot of UAPI and
"all possible data structures" structs declared in the kernel that we
were wading through only to find they weren't actually being used.

That said, I'm happy to send a patch to convert hashtable -- it's not
used so it can't break anything. ;)

-- 
Kees Cook