linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] vboxsf: Use flexible arrays for trailing string member
@ 2023-07-20 15:15 Kees Cook
  2023-07-25  9:00 ` Hans de Goede
  2023-07-26 21:55 ` Kees Cook
  0 siblings, 2 replies; 5+ messages in thread
From: Kees Cook @ 2023-07-20 15:15 UTC (permalink / raw)
  To: Hans de Goede
  Cc: Kees Cook, Larry Finger, linux-kernel, linux-fsdevel, linux-hardening

The declaration of struct shfl_string used trailing fake flexible arrays
for the string member. This was tripping FORTIFY_SOURCE since commit
df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3"). Replace the
utf8 and utf16 members with actual flexible arrays, drop the unused ucs2
member, and retriain a 2 byte padding to keep the structure size the same.

Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Closes: https://lore.kernel.org/lkml/ab3a70e9-60ed-0f13-e3d4-8866eaccc8c1@lwfinger.net/
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/vboxsf/shfl_hostintf.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/vboxsf/shfl_hostintf.h b/fs/vboxsf/shfl_hostintf.h
index aca829062c12..069a019c9247 100644
--- a/fs/vboxsf/shfl_hostintf.h
+++ b/fs/vboxsf/shfl_hostintf.h
@@ -68,9 +68,9 @@ struct shfl_string {
 
 	/** UTF-8 or UTF-16 string. Nul terminated. */
 	union {
-		u8 utf8[2];
-		u16 utf16[1];
-		u16 ucs2[1]; /* misnomer, use utf16. */
+		u8 legacy_padding[2];
+		DECLARE_FLEX_ARRAY(u8, utf8);
+		DECLARE_FLEX_ARRAY(u16, utf16);
 	} string;
 };
 VMMDEV_ASSERT_SIZE(shfl_string, 6);
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread
* Re: [PATCH] vboxsf: Use flexible arrays for trailing string member
  2023-07-20 15:15 [PATCH] vboxsf: Use flexible arrays for trailing string member Kees Cook
@ 2023-07-25  9:00 ` Hans de Goede
  2023-07-26 21:55 ` Kees Cook
  1 sibling, 0 replies; 5+ messages in thread
From: Hans de Goede @ 2023-07-25  9:00 UTC (permalink / raw)
  To: Kees Cook; +Cc: Larry Finger, linux-kernel, linux-fsdevel, linux-hardening

Hi Kees, Larry,

On 7/20/23 17:15, Kees Cook wrote:
> The declaration of struct shfl_string used trailing fake flexible arrays
> for the string member. This was tripping FORTIFY_SOURCE since commit
> df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3"). Replace the
> utf8 and utf16 members with actual flexible arrays, drop the unused ucs2
> member, and retriain a 2 byte padding to keep the structure size the same.
> 
> Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
> Closes: https://lore.kernel.org/lkml/ab3a70e9-60ed-0f13-e3d4-8866eaccc8c1@lwfinger.net/
> Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Kees, Larry thank you for fixing this while I was on vacation.

The patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Kees, I'm the vboxsf maintainer and it would be easiest for
me if you can include this in a future 6.5 fixes pull-request
to Linus if that is possible ?

Regards,

Hans



> ---
>  fs/vboxsf/shfl_hostintf.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/vboxsf/shfl_hostintf.h b/fs/vboxsf/shfl_hostintf.h
> index aca829062c12..069a019c9247 100644
> --- a/fs/vboxsf/shfl_hostintf.h
> +++ b/fs/vboxsf/shfl_hostintf.h
> @@ -68,9 +68,9 @@ struct shfl_string {
>  
>  	/** UTF-8 or UTF-16 string. Nul terminated. */
>  	union {
> -		u8 utf8[2];
> -		u16 utf16[1];
> -		u16 ucs2[1]; /* misnomer, use utf16. */
> +		u8 legacy_padding[2];
> +		DECLARE_FLEX_ARRAY(u8, utf8);
> +		DECLARE_FLEX_ARRAY(u16, utf16);
>  	} string;
>  };
>  VMMDEV_ASSERT_SIZE(shfl_string, 6);


^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH] vboxsf: Use flexible arrays for trailing string member
  2023-07-20 15:15 [PATCH] vboxsf: Use flexible arrays for trailing string member Kees Cook
  2023-07-25  9:00 ` Hans de Goede
@ 2023-07-26 21:55 ` Kees Cook
  2023-08-08 19:20   ` Larry Finger
  1 sibling, 1 reply; 5+ messages in thread
From: Kees Cook @ 2023-07-26 21:55 UTC (permalink / raw)
  To: Hans de Goede, Kees Cook
  Cc: Larry Finger, linux-kernel, linux-fsdevel, linux-hardening


On Thu, 20 Jul 2023 08:15:06 -0700, Kees Cook wrote:
> The declaration of struct shfl_string used trailing fake flexible arrays
> for the string member. This was tripping FORTIFY_SOURCE since commit
> df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3"). Replace the
> utf8 and utf16 members with actual flexible arrays, drop the unused ucs2
> member, and retriain a 2 byte padding to keep the structure size the same.
> 
> 
> [...]

Applied to for-linus/hardening, thanks!

[1/1] vboxsf: Use flexible arrays for trailing string member
      https://git.kernel.org/kees/c/a8f014ec6a21

Best regards,
-- 
Kees Cook


^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH] vboxsf: Use flexible arrays for trailing string member
  2023-07-26 21:55 ` Kees Cook
@ 2023-08-08 19:20   ` Larry Finger
  2023-08-08 21:01     ` Kees Cook
  0 siblings, 1 reply; 5+ messages in thread
From: Larry Finger @ 2023-08-08 19:20 UTC (permalink / raw)
  To: Kees Cook, Hans de Goede; +Cc: linux-kernel, linux-fsdevel, linux-hardening

On 7/26/23 16:55, Kees Cook wrote:
> 
> On Thu, 20 Jul 2023 08:15:06 -0700, Kees Cook wrote:
>> The declaration of struct shfl_string used trailing fake flexible arrays
>> for the string member. This was tripping FORTIFY_SOURCE since commit
>> df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3"). Replace the
>> utf8 and utf16 members with actual flexible arrays, drop the unused ucs2
>> member, and retriain a 2 byte padding to keep the structure size the same.
>>
>>
>> [...]
> 
> Applied to for-linus/hardening, thanks!
> 
> [1/1] vboxsf: Use flexible arrays for trailing string member
>        https://git.kernel.org/kees/c/a8f014ec6a21

Kees,

This patch has not been applied to kernel 6.5-rc5. Is there some problem?

Larry



^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH] vboxsf: Use flexible arrays for trailing string member
  2023-08-08 19:20   ` Larry Finger
@ 2023-08-08 21:01     ` Kees Cook
  0 siblings, 0 replies; 5+ messages in thread
From: Kees Cook @ 2023-08-08 21:01 UTC (permalink / raw)
  To: Larry Finger; +Cc: Hans de Goede, linux-kernel, linux-fsdevel, linux-hardening

On Tue, Aug 08, 2023 at 02:20:06PM -0500, Larry Finger wrote:
> On 7/26/23 16:55, Kees Cook wrote:
> > 
> > On Thu, 20 Jul 2023 08:15:06 -0700, Kees Cook wrote:
> > > The declaration of struct shfl_string used trailing fake flexible arrays
> > > for the string member. This was tripping FORTIFY_SOURCE since commit
> > > df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3"). Replace the
> > > utf8 and utf16 members with actual flexible arrays, drop the unused ucs2
> > > member, and retriain a 2 byte padding to keep the structure size the same.
> > > 
> > > 
> > > [...]
> > 
> > Applied to for-linus/hardening, thanks!
> > 
> > [1/1] vboxsf: Use flexible arrays for trailing string member
> >        https://git.kernel.org/kees/c/a8f014ec6a21
> 
> Kees,
> 
> This patch has not been applied to kernel 6.5-rc5. Is there some problem?

Hi! Sorry, I was waiting for linux-next testing, and then got distracted
on Friday. I will send the PR to Linus today.

Thanks for the poke!

-Kees

-- 
Kees Cook

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-08-08 21:20 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-07-20 15:15 [PATCH] vboxsf: Use flexible arrays for trailing string member Kees Cook
2023-07-25  9:00 ` Hans de Goede
2023-07-26 21:55 ` Kees Cook
2023-08-08 19:20   ` Larry Finger
2023-08-08 21:01     ` Kees Cook

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).