linux-kernel - Re: [PATCH] vboxsf: Add __nonstring annotations for unterminated strings

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Message-ID: <7ceea724-4e9e-409e-88fa-0d186096744f@redhat.com>
Date: Tue, 11 Mar 2025 11:09:49 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: Kees Cook <kees@...nel.org>
Cc: Brahmajit Das <brahmajit.xyz@...il.com>,
 Christian Brauner <brauner@...nel.org>, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] vboxsf: Add __nonstring annotations for unterminated
 strings

Hi,

On 10-Mar-25 11:25 PM, 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.
> 
> This effectively reverts the change in 4e7487245abc ("vboxsf: fix building
> with GCC 15"), to add the annotation that has other uses (i.e. warning
> if the string is ever used with C string APIs).
> 
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Brahmajit Das <brahmajit.xyz@...il.com>
> Cc: Christian Brauner <brauner@...nel.org>
> Cc: linux-fsdevel@...r.kernel.org
> Signed-off-by: Kees Cook <kees@...nel.org>

Thanks, patch looks good to me:

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

Regards,

Hans



> ---
>  fs/vboxsf/super.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/vboxsf/super.c b/fs/vboxsf/super.c
> index 1d94bb784108..0bc96ab6580b 100644
> --- a/fs/vboxsf/super.c
> +++ b/fs/vboxsf/super.c
> @@ -21,8 +21,7 @@
>  
>  #define VBOXSF_SUPER_MAGIC 0x786f4256 /* 'VBox' little endian */
>  
> -static const unsigned char VBSF_MOUNT_SIGNATURE[4] = { '\000', '\377', '\376',
> -						       '\375' };
> +static const unsigned char VBSF_MOUNT_SIGNATURE[4] __nonstring = "\000\377\376\375";
>  
>  static int follow_symlinks;
>  module_param(follow_symlinks, int, 0444);