[PATCH v2] net: macb: Add __nonstring annotations for unterminated strings

[PATCH v2] net: macb: Add __nonstring annotations for unterminated strings

[Kees Cook]

When a character array without a terminating NUL character has a static
initializer, GCC 15's -Wunterminated-string-initialization will only
warn if the array lacks the "nonstring" attribute[1]. Mark the arrays
with __nonstring to and correctly identify the char array as "not a C
string" and thereby eliminate the warning.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
Signed-off-by: Kees Cook <kees@kernel.org>
---
 v1: https://lore.kernel.org/lkml/20250310222415.work.815-kees@kernel.org/
 v2: switch to __nonstring annotation
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
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: netdev@vger.kernel.org
---
 drivers/net/ethernet/cadence/macb.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 2847278d9cd4..003483073223 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -1027,7 +1027,7 @@ struct gem_stats {
  * this register should contribute to.
  */
 struct gem_statistic {
-	char stat_string[ETH_GSTRING_LEN];
+	char stat_string[ETH_GSTRING_LEN] __nonstring;
 	int offset;
 	u32 stat_bits;
 };
@@ -1068,6 +1068,7 @@ static const struct gem_statistic gem_statistics[] = {
 	GEM_STAT_TITLE(TX512CNT, "tx_512_1023_byte_frames"),
 	GEM_STAT_TITLE(TX1024CNT, "tx_1024_1518_byte_frames"),
 	GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"),
+
 	GEM_STAT_TITLE_BITS(TXURUNCNT, "tx_underrun",
 			    GEM_BIT(NDS_TXERR)|GEM_BIT(NDS_TXFIFOERR)),
 	GEM_STAT_TITLE_BITS(SNGLCOLLCNT, "tx_single_collision_frames",
-- 
2.34.1

Re: [PATCH v2] net: macb: Add __nonstring annotations for unterminated strings

[Bill Wendling]

On Tue, Mar 11, 2025 at 3:44 PM Kees Cook <kees@kernel.org> wrote:
>
> When a character array without a terminating NUL character has a static
> initializer, GCC 15's -Wunterminated-string-initialization will only
> warn if the array lacks the "nonstring" attribute[1]. Mark the arrays
> with __nonstring to and correctly identify the char array as "not a C

s/__nonstring to and correctly/__nonstring to correctly/ ?

> string" and thereby eliminate the warning.
>
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
> Signed-off-by: Kees Cook <kees@kernel.org>
> ---
>  v1: https://lore.kernel.org/lkml/20250310222415.work.815-kees@kernel.org/
>  v2: switch to __nonstring annotation
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
> Cc: Andrew Lunn <andrew+netdev@lunn.ch>
> 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: netdev@vger.kernel.org
> ---
>  drivers/net/ethernet/cadence/macb.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index 2847278d9cd4..003483073223 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -1027,7 +1027,7 @@ struct gem_stats {
>   * this register should contribute to.
>   */
>  struct gem_statistic {
> -       char stat_string[ETH_GSTRING_LEN];
> +       char stat_string[ETH_GSTRING_LEN] __nonstring;
>         int offset;
>         u32 stat_bits;
>  };
> @@ -1068,6 +1068,7 @@ static const struct gem_statistic gem_statistics[] = {
>         GEM_STAT_TITLE(TX512CNT, "tx_512_1023_byte_frames"),
>         GEM_STAT_TITLE(TX1024CNT, "tx_1024_1518_byte_frames"),
>         GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"),
> +

Is this an errant inclusion? :-)

Reviewed-by: Bill Wendling <morbo@google.com>

>         GEM_STAT_TITLE_BITS(TXURUNCNT, "tx_underrun",
>                             GEM_BIT(NDS_TXERR)|GEM_BIT(NDS_TXFIFOERR)),
>         GEM_STAT_TITLE_BITS(SNGLCOLLCNT, "tx_single_collision_frames",
> --
> 2.34.1
>
>

Re: [PATCH v2] net: macb: Add __nonstring annotations for unterminated strings

[Kees Cook]

On Tue, Mar 11, 2025 at 04:04:24PM -0700, Bill Wendling wrote:
> On Tue, Mar 11, 2025 at 3:44 PM Kees Cook <kees@kernel.org> wrote:
> >
> > When a character array without a terminating NUL character has a static
> > initializer, GCC 15's -Wunterminated-string-initialization will only
> > warn if the array lacks the "nonstring" attribute[1]. Mark the arrays
> > with __nonstring to and correctly identify the char array as "not a C
> 
> s/__nonstring to and correctly/__nonstring to correctly/ ?

Whoops. Rewriting glitch. Yes, "and" should be dropped. I will fix this
locally for all the patches with the same language and send v3 for this
one.

> 
> > string" and thereby eliminate the warning.
> >
> > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
> > Signed-off-by: Kees Cook <kees@kernel.org>
> > ---
> >  v1: https://lore.kernel.org/lkml/20250310222415.work.815-kees@kernel.org/
> >  v2: switch to __nonstring annotation
> > Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> > Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
> > Cc: Andrew Lunn <andrew+netdev@lunn.ch>
> > 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: netdev@vger.kernel.org
> > ---
> >  drivers/net/ethernet/cadence/macb.h | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> > index 2847278d9cd4..003483073223 100644
> > --- a/drivers/net/ethernet/cadence/macb.h
> > +++ b/drivers/net/ethernet/cadence/macb.h
> > @@ -1027,7 +1027,7 @@ struct gem_stats {
> >   * this register should contribute to.
> >   */
> >  struct gem_statistic {
> > -       char stat_string[ETH_GSTRING_LEN];
> > +       char stat_string[ETH_GSTRING_LEN] __nonstring;
> >         int offset;
> >         u32 stat_bits;
> >  };
> > @@ -1068,6 +1068,7 @@ static const struct gem_statistic gem_statistics[] = {
> >         GEM_STAT_TITLE(TX512CNT, "tx_512_1023_byte_frames"),
> >         GEM_STAT_TITLE(TX1024CNT, "tx_1024_1518_byte_frames"),
> >         GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"),
> > +
> 
> Is this an errant inclusion? :-)

Ah, yeah, I had removed the truncation change but the whitespace change
stuck around. Also fixing!

> 
> Reviewed-by: Bill Wendling <morbo@google.com>

Thanks!

-Kees

-- 
Kees Cook

Re: [PATCH v2] net: macb: Add __nonstring annotations for unterminated strings

[Simon Horman]

On Tue, Mar 11, 2025 at 03:44:16PM -0700, Kees Cook wrote:
> When a character array without a terminating NUL character has a static
> initializer, GCC 15's -Wunterminated-string-initialization will only
> warn if the array lacks the "nonstring" attribute[1]. Mark the arrays
> with __nonstring to and correctly identify the char array as "not a C
> string" and thereby eliminate the warning.
> 
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
> Signed-off-by: Kees Cook <kees@kernel.org>
> ---
>  v1: https://lore.kernel.org/lkml/20250310222415.work.815-kees@kernel.org/
>  v2: switch to __nonstring annotation
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
> Cc: Andrew Lunn <andrew+netdev@lunn.ch>
> 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: netdev@vger.kernel.org
> ---
>  drivers/net/ethernet/cadence/macb.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index 2847278d9cd4..003483073223 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -1027,7 +1027,7 @@ struct gem_stats {
>   * this register should contribute to.
>   */
>  struct gem_statistic {
> -	char stat_string[ETH_GSTRING_LEN];
> +	char stat_string[ETH_GSTRING_LEN] __nonstring;

Hi Kees, all,

I see where this is going, and I have no objections to it.
But a member called *_string which is annotated as __nonstring
does seem a somewhat unintuitive.

>  	int offset;
>  	u32 stat_bits;
>  };
> @@ -1068,6 +1068,7 @@ static const struct gem_statistic gem_statistics[] = {
>  	GEM_STAT_TITLE(TX512CNT, "tx_512_1023_byte_frames"),
>  	GEM_STAT_TITLE(TX1024CNT, "tx_1024_1518_byte_frames"),
>  	GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"),
> +
>  	GEM_STAT_TITLE_BITS(TXURUNCNT, "tx_underrun",
>  			    GEM_BIT(NDS_TXERR)|GEM_BIT(NDS_TXFIFOERR)),
>  	GEM_STAT_TITLE_BITS(SNGLCOLLCNT, "tx_single_collision_frames",
> -- 
> 2.34.1
> 
>