[PATCH v2] p54: Replace zero-length array of trailing structs with flex-array

[PATCH v2] p54: Replace zero-length array of trailing structs with flex-array

[Kees Cook]

Zero-length arrays are deprecated[1] and are being replaced with
flexible array members in support of the ongoing efforts to tighten the
FORTIFY_SOURCE routines on memcpy(), correctly instrument array indexing
with UBSAN_BOUNDS, and to globally enable -fstrict-flex-arrays=3.

Replace zero-length array with flexible-array member.

This results in no differences in binary output (most especially because
struct pda_antenna_gain is unused). The struct is kept for future
reference.

[1] https://github.com/KSPP/linux/issues/78

Cc: Christian Lamparter <chunkeey@googlemail.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v2:
- convert normally (chunkeey)
v1: https://lore.kernel.org/lkml/20221118210639.never.072-kees@kernel.org/
---
 drivers/net/wireless/intersil/p54/eeprom.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intersil/p54/eeprom.h b/drivers/net/wireless/intersil/p54/eeprom.h
index 1d0aaf54389a..641c4e79879e 100644
--- a/drivers/net/wireless/intersil/p54/eeprom.h
+++ b/drivers/net/wireless/intersil/p54/eeprom.h
@@ -108,10 +108,10 @@ struct pda_country {
 } __packed;
 
 struct pda_antenna_gain {
-	struct {
+	DECLARE_FLEX_ARRAY(struct {
 		u8 gain_5GHz;	/* 0.25 dBi units */
 		u8 gain_2GHz;	/* 0.25 dBi units */
-	} __packed antenna[0];
+	} __packed, antenna);
 } __packed;
 
 struct pda_custom_wrapper {
-- 
2.34.1

Re: [PATCH v2] p54: Replace zero-length array of trailing structs with flex-array

[Christian Lamparter]

On 11/19/22 00:42, Kees Cook wrote:
> Zero-length arrays are deprecated[1] and are being replaced with
> flexible array members in support of the ongoing efforts to tighten the
> FORTIFY_SOURCE routines on memcpy(), correctly instrument array indexing
> with UBSAN_BOUNDS, and to globally enable -fstrict-flex-arrays=3.
> 
> Replace zero-length array with flexible-array member.
> 
> This results in no differences in binary output (most especially because
> struct pda_antenna_gain is unused). The struct is kept for future
> reference.
> 
> [1] https://github.com/KSPP/linux/issues/78
> 

Thank you!

> Cc: Christian Lamparter <chunkeey@googlemail.com>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Lamparter <chunkeey@gmail.com>
> ---
> v2:
> - convert normally (chunkeey)
> v1: https://lore.kernel.org/lkml/20221118210639.never.072-kees@kernel.org/
> ---
>   drivers/net/wireless/intersil/p54/eeprom.h | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/intersil/p54/eeprom.h b/drivers/net/wireless/intersil/p54/eeprom.h
> index 1d0aaf54389a..641c4e79879e 100644
> --- a/drivers/net/wireless/intersil/p54/eeprom.h
> +++ b/drivers/net/wireless/intersil/p54/eeprom.h
> @@ -108,10 +108,10 @@ struct pda_country {
>   } __packed;
>   
>   struct pda_antenna_gain {
> -	struct {
> +	DECLARE_FLEX_ARRAY(struct {
>   		u8 gain_5GHz;	/* 0.25 dBi units */
>   		u8 gain_2GHz;	/* 0.25 dBi units */
> -	} __packed antenna[0];
> +	} __packed, antenna);
>   } __packed;
>   
>   struct pda_custom_wrapper {

Re: [PATCH v2] p54: Replace zero-length array of trailing structs with flex-array

[Kalle Valo]

Kees Cook <keescook@chromium.org> writes:

> Zero-length arrays are deprecated[1] and are being replaced with
> flexible array members in support of the ongoing efforts to tighten the
> FORTIFY_SOURCE routines on memcpy(), correctly instrument array indexing
> with UBSAN_BOUNDS, and to globally enable -fstrict-flex-arrays=3.
>
> Replace zero-length array with flexible-array member.
>
> This results in no differences in binary output (most especially because
> struct pda_antenna_gain is unused). The struct is kept for future
> reference.
>
> [1] https://github.com/KSPP/linux/issues/78
>
> Cc: Christian Lamparter <chunkeey@googlemail.com>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

I'll add "wifi:".

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [v2] wifi: p54: Replace zero-length array of trailing structs with flex-array

[Kalle Valo]

Kees Cook <keescook@chromium.org> wrote:

> Zero-length arrays are deprecated[1] and are being replaced with
> flexible array members in support of the ongoing efforts to tighten the
> FORTIFY_SOURCE routines on memcpy(), correctly instrument array indexing
> with UBSAN_BOUNDS, and to globally enable -fstrict-flex-arrays=3.
> 
> Replace zero-length array with flexible-array member.
> 
> This results in no differences in binary output (most especially because
> struct pda_antenna_gain is unused). The struct is kept for future
> reference.
> 
> [1] https://github.com/KSPP/linux/issues/78
> 
> Cc: Christian Lamparter <chunkeey@googlemail.com>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Acked-by: Christian Lamparter <chunkeey@gmail.com>

Patch applied to wireless-next.git, thanks.

3b79d4bad3a0 wifi: p54: Replace zero-length array of trailing structs with flex-array

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20221118234240.gonna.369-kees@kernel.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches