linux-kernel - Re: [PATCH] drm/i915/gvt: Add __nonstring annotations for unterminated strings

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Message-ID: <01070195c306db7f-9f28efdd-9456-4db3-b6c6-343298bd571b-000000@eu-central-1.amazonses.com>
Date: Sun, 23 Mar 2025 12:42:41 +0000
From: Damian Tometzki <damian@...cv-rocks.de>
To: Kees Cook <kees@...nel.org>
Cc: Zhenyu Wang <zhenyuw@...ux.intel.com>, 
	Zhi Wang <zhi.wang.linux@...il.com>, 
	Jani Nikula <jani.nikula@...ux.intel.com>, 
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, 
	Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	Tvrtko Ursulin <tursulin@...ulin.net>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	intel-gvt-dev@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH] drm/i915/gvt: Add __nonstring annotations for
 unterminated strings

On Mon, 10. Mar 15:23, 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]
> Cc: Zhenyu Wang <zhenyuw@...ux.intel.com>
> Cc: Zhi Wang <zhi.wang.linux@...il.com>
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Cc: Tvrtko Ursulin <tursulin@...ulin.net>
> Cc: David Airlie <airlied@...il.com>
> Cc: Simona Vetter <simona@...ll.ch>
> Cc: intel-gvt-dev@...ts.freedesktop.org
> Cc: intel-gfx@...ts.freedesktop.org
> Cc: dri-devel@...ts.freedesktop.org
> Signed-off-by: Kees Cook <kees@...nel.org>
> ---
>  drivers/gpu/drm/i915/gvt/opregion.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/opregion.c b/drivers/gpu/drm/i915/gvt/opregion.c
> index 509f9ccae3a9..f701638d3145 100644
> --- a/drivers/gpu/drm/i915/gvt/opregion.c
> +++ b/drivers/gpu/drm/i915/gvt/opregion.c
> @@ -43,7 +43,7 @@
>  #define DEVICE_TYPE_EFP4   0x10
>  
>  struct opregion_header {
> -	u8 signature[16];
> +	u8 signature[16] __nonstring;
>  	u32 size;
>  	u32 opregion_ver;
>  	u8 bios_ver[32];
> @@ -222,7 +222,7 @@ int intel_vgpu_init_opregion(struct intel_vgpu *vgpu)
>  	u8 *buf;
>  	struct opregion_header *header;
>  	struct vbt v;
> -	const char opregion_signature[16] = OPREGION_SIGNATURE;
> +	const char opregion_signature[16] __nonstring = OPREGION_SIGNATURE;
>  
>  	gvt_dbg_core("init vgpu%d opregion\n", vgpu->id);
>  	vgpu_opregion(vgpu)->va = (void *)__get_free_pages(GFP_KERNEL |
> -- 
> 2.34.1
> 
Hello together,

it doesnt resolve the build issue with gcc15 gcc (GCC) 15.0.1 20250228

CC [M]  drivers/gpu/drm/i915/gvt/scheduler.o
/home/damian/kernel/linux/drivers/gpu/drm/i915/gvt/opregion.c: In function ‘intel_vgpu_init_opregion’:
/home/damian/kernel/linux/drivers/gpu/drm/i915/gvt/opregion.c:35:28: error: initializer-string for array of ‘char’ is too long [-Werror=unterminated-string-initialization]
   35 | #define OPREGION_SIGNATURE "IntelGraphicsMem"
      |                            ^~~~~~~~~~~~~~~~~~
/home/damian/kernel/linux/drivers/gpu/drm/i915/gvt/opregion.c:225:57: note: in expansion of macro ‘OPREGION_SIGNATURE’
  225 |         const char opregion_signature[16] __nonstring = OPREGION_SIGNATURE;
      |                                                         ^~~~~~~~~~~~~~~~~~
  CC [M]  drivers/gpu/drm/i915/gvt/trace_points.o
cc1: all warnings being treated as errors
make[7]: *** [/home/damian/kernel/linux/scripts/Makefile.build:207: drivers/gpu/drm/i915/gvt/opregion.o] Error 1
make[7]: *** Waiting for unfinished jobs....
  CC [M]  drivers/gpu/drm/i915/gvt/vgpu.o
make[6]: *** [/home/damian/kernel/linux/scripts/Makefile.build:465: drivers/gpu/drm/i915] Error 2
make[5]: *** [/home/damian/kernel/linux/s


-- 
VG
Damian Tometzki