2023-07-31 02:03:18

by Atul Raut

Subject: [PATCH] ath6kl: Replace zero-length arrays with DECLARE_FLEX_ARRAY() helper

Because zero-length arrays are obsolete, replacing them with
C99 flexible-array members.
Instead of defining a zero-length array, use the new
DECLARE_FLEX_ARRAY() auxiliary macro.

This fixes warnings such as:
./drivers/net/wireless/ath/ath6kl/usb.c:109:8-12: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)

Signed-off-by: Atul Raut <[email protected]>
---
drivers/net/wireless/ath/ath6kl/usb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
index 5220809841a6..bb3771a3897c 100644
--- a/drivers/net/wireless/ath/ath6kl/usb.c
+++ b/drivers/net/wireless/ath/ath6kl/usb.c
@@ -106,7 +106,7 @@ struct ath6kl_usb_ctrl_diag_cmd_write {
__le32 cmd;
__le32 address;
__le32 value;
- __le32 _pad[1];
+ DECLARE_FLEX_ARRAY(__le32, _pad);
} __packed;

struct ath6kl_usb_ctrl_diag_cmd_read {
--
2.34.1

2023-07-31 06:20:30

by Greg KH

Subject: Re: [PATCH] ath6kl: Replace zero-length arrays with DECLARE_FLEX_ARRAY() helper

On Sun, Jul 30, 2023 at 06:29:41PM -0700, Atul Raut wrote:
> Because zero-length arrays are obsolete, replacing them with
> C99 flexible-array members.
> Instead of defining a zero-length array, use the new
> DECLARE_FLEX_ARRAY() auxiliary macro.
>
> This fixes warnings such as:
> ./drivers/net/wireless/ath/ath6kl/usb.c:109:8-12: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
>
> Signed-off-by: Atul Raut <[email protected]>
> ---
> drivers/net/wireless/ath/ath6kl/usb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
> index 5220809841a6..bb3771a3897c 100644
> --- a/drivers/net/wireless/ath/ath6kl/usb.c
> +++ b/drivers/net/wireless/ath/ath6kl/usb.c
> @@ -106,7 +106,7 @@ struct ath6kl_usb_ctrl_diag_cmd_write {
> __le32 cmd;
> __le32 address;
> __le32 value;
> - __le32 _pad[1];
> + DECLARE_FLEX_ARRAY(__le32, _pad);

This is not a 0 length array, or a variable array. Look at the work
done on the hardening mailing list for more details, I think this is
wrong.

good luck!

greg k-h

2023-08-01 14:44:55

by Kalle Valo

Subject: Re: [PATCH] ath6kl: Replace zero-length arrays with DECLARE_FLEX_ARRAY() helper

Greg KH <[email protected]> writes:

> On Sun, Jul 30, 2023 at 06:29:41PM -0700, Atul Raut wrote:
>
>> Because zero-length arrays are obsolete, replacing them with
>> C99 flexible-array members.
>> Instead of defining a zero-length array, use the new
>> DECLARE_FLEX_ARRAY() auxiliary macro.
>>
>> This fixes warnings such as:
>> ./drivers/net/wireless/ath/ath6kl/usb.c:109:8-12: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
>>
>> Signed-off-by: Atul Raut <[email protected]>
>> ---
>> drivers/net/wireless/ath/ath6kl/usb.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
>> index 5220809841a6..bb3771a3897c 100644
>> --- a/drivers/net/wireless/ath/ath6kl/usb.c
>> +++ b/drivers/net/wireless/ath/ath6kl/usb.c
>> @@ -106,7 +106,7 @@ struct ath6kl_usb_ctrl_diag_cmd_write {
>> __le32 cmd;
>> __le32 address;
>> __le32 value;
>> - __le32 _pad[1];
>> + DECLARE_FLEX_ARRAY(__le32, _pad);
>
> This is not a 0 length array, or a variable array. Look at the work
> done on the hardening mailing list for more details, I think this is
> wrong.

I agree with Greg, this is just padding and _pad is not even used
anywhere in ath6kl. Though use of [1] is strange here, '__le32 _pad;'
would be enough.

--
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