Re: [PATCH] auditsc: Implement a workaround for a GCC bug triggered by task comm changes

[Paul Moore]

On Tue, Dec 3, 2024 at 1:04 AM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> From: Yafang shao <laoar.shao@xxxxxxxxx>
>
> A build failure has been reported with the following details:
>
>    In file included from include/linux/string.h:390,
>                     from include/linux/bitmap.h:13,
>                     from include/linux/cpumask.h:12,
>                     from include/linux/smp.h:13,
>                     from include/linux/lockdep.h:14,
>                     from include/linux/spinlock.h:63,
>                     from include/linux/wait.h:9,
>                     from include/linux/wait_bit.h:8,
>                     from include/linux/fs.h:6,
>                     from kernel/auditsc.c:37:
>    In function 'sized_strscpy',
>        inlined from '__audit_ptrace' at kernel/auditsc.c:2732:2:
> >> include/linux/fortify-string.h:293:17: error: call to '__write_overflow' declared with attribute error: detected write beyond size of object (1st parameter)
>      293 |                 __write_overflow();
>          |                 ^~~~~~~~~~~~~~~~~~
>    In function 'sized_strscpy',
>        inlined from 'audit_signal_info_syscall' at kernel/auditsc.c:2759:3:
> >> include/linux/fortify-string.h:293:17: error: call to '__write_overflow' declared with attribute error: detected write beyond size of object (1st parameter)
>      293 |                 __write_overflow();
>          |                 ^~~~~~~~~~~~~~~~~~
>
> The issue appears to be a GCC bug, though the root cause remains
> unclear at this time. For now, let's implement a workaround.
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202410171420.1V00ICVG-lkp@xxxxxxxxx/
> Reported-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/20241128182435.57a1ea6f@xxxxxxxxxxxxxxxxxx/
> Reported-by: "Zhuo, Qiuxu" <qiuxu.zhuo@xxxxxxxxx>
> Closes: https://lore.kernel.org/all/CY8PR11MB71348E568DBDA576F17DAFF389362@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> Originally-by: Kees Cook <kees@xxxxxxxxxx>
> Link: https://lore.kernel.org/linux-hardening/202410171059.C2C395030@keescook/
> Signed-off-by: Yafang shao <laoar.shao@xxxxxxxxx>
> Tested-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> ---
>  kernel/auditsc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Thanks, does anyone have a link to the GCC bug report?  We really
should mention that in the commit description and/or metadata.

> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 279ba5c420a4..561d96affe9f 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2728,8 +2728,8 @@ void __audit_ptrace(struct task_struct *t)
>         context->target_auid = audit_get_loginuid(t);
>         context->target_uid = task_uid(t);
>         context->target_sessionid = audit_get_sessionid(t);
> -       security_task_getlsmprop_obj(t, &context->target_ref);
>         strscpy(context->target_comm, t->comm);
> +       security_task_getlsmprop_obj(t, &context->target_ref);
>  }
>
>  /**
> @@ -2755,8 +2755,8 @@ int audit_signal_info_syscall(struct task_struct *t)
>                 ctx->target_auid = audit_get_loginuid(t);
>                 ctx->target_uid = t_uid;
>                 ctx->target_sessionid = audit_get_sessionid(t);
> -               security_task_getlsmprop_obj(t, &ctx->target_ref);
>                 strscpy(ctx->target_comm, t->comm);
> +               security_task_getlsmprop_obj(t, &ctx->target_ref);
>                 return 0;
>         }
>
> --
> 2.43.5

-- 
paul-moore.com