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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <01070195cec129de-3a185083-9c9f-451c-a7f9-3798f9eb5954-000000@eu-central-1.amazonses.com>
Date: Tue, 25 Mar 2025 19:22:00 +0000
From: Damian Tometzki <damian@...cv-rocks.de>
To: Nicolas Chauvet <kwizart@...il.com>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>, Kees Cook <kees@...nel.org>, 
	Zhenyu Wang <zhenyuw@...ux.intel.com>, 
	Zhi Wang <zhi.wang.linux@...il.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, 24. Mar 22:19, Nicolas Chauvet wrote:
> Le lun. 24 mars 2025 à 13:54, Jani Nikula
> <jani.nikula@...ux.intel.com> a écrit :
> >
> > On Sun, 23 Mar 2025, Damian Tometzki <damian@...cv-rocks.de> wrote:
> > > 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;
> >
> > Why would this annotation be needed? It's not treated as a string
> > anywhere, and it's u8 not char.
> >
> > >>      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
> >
> > What about this?
> >
> > IMO it's anyway good practice to use sizeof(dest) rather than
> > sizeof(src) for memcpy.
> >
> >
> > diff --git a/drivers/gpu/drm/i915/gvt/opregion.c b/drivers/gpu/drm/i915/gvt/opregion.c
> > index 509f9ccae3a9..dbad4d853d3a 100644
> > --- a/drivers/gpu/drm/i915/gvt/opregion.c
> > +++ b/drivers/gpu/drm/i915/gvt/opregion.c
> > @@ -222,7 +222,6 @@ 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;
> >
> >         gvt_dbg_core("init vgpu%d opregion\n", vgpu->id);
> >         vgpu_opregion(vgpu)->va = (void *)__get_free_pages(GFP_KERNEL |
> > @@ -236,8 +235,10 @@ int intel_vgpu_init_opregion(struct intel_vgpu *vgpu)
> >         /* emulated opregion with VBT mailbox only */
> >         buf = (u8 *)vgpu_opregion(vgpu)->va;
> >         header = (struct opregion_header *)buf;
> > -       memcpy(header->signature, opregion_signature,
> > -              sizeof(opregion_signature));
> > +
> > +       static_assert(sizeof(header->signature) == sizeof(OPREGION_SIGNATURE) - 1);
> > +       memcpy(header->signature, OPREGION_SIGNATURE, sizeof(header->signature));
> > +
> >         header->size = 0x8;
> >         header->opregion_ver = 0x02000000;
> >         header->mboxes = MBOX_VBT;
> >
> >
> >
> > --
> > Jani Nikula, Intel
> 
> This patch does solve the build issue with gcc-15 on Fedora-42
> (gcc-15.0.1-0.9.fc42.x86_64).
> https://copr.fedorainfracloud.org/coprs/kwizart/kernel-longterm-6.12/build/8812754/
testet-by Damian Tometzki
Thanks
Damian

> 
> Thanks.

-- 
VG
Damian Tometzki