2022-02-16 19:55:16

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH] uapi: wireless: Replace zero-length array with flexible-array member

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
include/uapi/linux/wireless.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
index 08967b3f19c8..3c2ad5fae17f 100644
--- a/include/uapi/linux/wireless.h
+++ b/include/uapi/linux/wireless.h
@@ -835,7 +835,7 @@ struct iw_encode_ext {
* individual keys */
__u16 alg; /* IW_ENCODE_ALG_* */
__u16 key_len;
- __u8 key[0];
+ __u8 key[];
};

/* SIOCSIWMLME data */
--
2.27.0


2022-02-16 21:26:20

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH] uapi: wireless: Replace zero-length array with flexible-array member

On Wed, Feb 16, 2022 at 01:53:06PM -0600, Gustavo A. R. Silva wrote:
> There is a regular need in the kernel to provide a way to declare
> having a dynamically sized set of trailing elements in a structure.
> Kernel code should always use “flexible array members”[1] for these
> cases. The older style of one-element or zero-length arrays should
> no longer be used[2].
>
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
>
> Link: https://github.com/KSPP/linux/issues/78
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

This UAPI change should be fine for any compiler that understood the
older "[0]" syntax.

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook

2022-03-26 15:27:43

by Gustavo A. R. Silva

[permalink] [raw]
Subject: Re: [PATCH] uapi: wireless: Replace zero-length array with flexible-array member

On Wed, Feb 16, 2022 at 12:36:27PM -0800, Kees Cook wrote:
> On Wed, Feb 16, 2022 at 01:53:06PM -0600, Gustavo A. R. Silva wrote:
> > There is a regular need in the kernel to provide a way to declare
> > having a dynamically sized set of trailing elements in a structure.
> > Kernel code should always use “flexible array members”[1] for these
> > cases. The older style of one-element or zero-length arrays should
> > no longer be used[2].
> >
> > [1] https://en.wikipedia.org/wiki/Flexible_array_member
> > [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
> >
> > Link: https://github.com/KSPP/linux/issues/78
> > Signed-off-by: Gustavo A. R. Silva <[email protected]>
>
> This UAPI change should be fine for any compiler that understood the
> older "[0]" syntax.
>
> Reviewed-by: Kees Cook <[email protected]>

Hi all,

Friendly ping: can someone take this, please?

...I can take this in my -next tree in the meantime.

Thanks
--
Gustavo