Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs

[Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>]

Am 21.12.2015 um 01:03 schrieb Mickaël Salaün:
> This fix two related bugs:
> * PTRACE_GETREGS doesn't get the right orig_ax (syscall) value
> * PTRACE_SETREGS can't set the orig_ax value (erased by initial value)
> 
> Remove the now useless and error-prone get_syscall().
> 
> Signed-off-by: Mickaël Salaün <mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
> Cc: Jeff Dike <jdike-OPE4K8JWMJJBDgjK7y7TUQ@public.gmane.org>
> Cc: Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>
> Cc: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Cc: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
> Cc: Will Drewry <wad-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Cc: Thomas Meyer <thomas-VsYtu1Qij5c@public.gmane.org>
> Cc: Nicolas Iooss <nicolas.iooss_linux-oWGTIYur0i8@public.gmane.org>
> Cc: Anton Ivanov <aivanov-43mecJUBy8ZBDgjK7y7TUQ@public.gmane.org>
> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: user-mode-linux-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> Cc: user-mode-linux-user-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> Cc: Meredydd Luff <meredydd-zPN50pYk8eUaUu29zAJCuw@public.gmane.org>
> Cc: David Drysdale <drysdale-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> ---
>  arch/um/kernel/skas/syscall.c   | 7 ++++++-
>  arch/um/os-Linux/skas/process.c | 7 -------
>  2 files changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
> index 1683b8e..65f0d1a 100644
> --- a/arch/um/kernel/skas/syscall.c
> +++ b/arch/um/kernel/skas/syscall.c
> @@ -7,6 +7,7 @@
>  #include <linux/ptrace.h>
>  #include <kern_util.h>
>  #include <sysdep/ptrace.h>
> +#include <sysdep/ptrace_user.h>
>  #include <sysdep/syscalls.h>
>  #include <os.h>
>  
> @@ -16,12 +17,16 @@ void handle_syscall(struct uml_pt_regs *r)
>  	long result;
>  	int syscall;
>  
> +	/* Save the syscall register. */
> +	UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
> +
>  	if (syscall_trace_enter(regs)) {
>  		result = -ENOSYS;
>  		goto out;
>  	}
>  
> -	syscall = get_syscall(r);
> +	/* Get the syscall after being potentially updated with ptrace. */
> +	syscall = UPT_SYSCALL_NR(r);

Doesn't this break the support for changing syscall numbers using PTRACE_SETREGS?

Thanks,
//richard