[PATCH] nptl: initialize cpu_id_start prior to rseq registration

[Mathieu Desnoyers]

On 2024-11-20 14:15, Michael Jeanson wrote:
> When adding explicit initialization of rseq fields prior to
> registration, I glossed over the fact that 'cpu_id_start' is also
> documented as initialized by user-space.
> 
> While current kernels don't validate the content of this field on
> registration, future ones could.
> 
> Signed-off-by: Michael Jeanson <mjeanson@efficios.com>

Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

> ---
> Cc: Florian Weimer <fweimer@redhat.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> ---
>   sysdeps/unix/sysv/linux/rseq-internal.h | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
> index 37a8f630b6..ef3eab1fef 100644
> --- a/sysdeps/unix/sysv/linux/rseq-internal.h
> +++ b/sysdeps/unix/sysv/linux/rseq-internal.h
> @@ -56,6 +56,7 @@ rseq_register_current_thread (struct pthread *self, bool do_rseq)
>            registration, there is no guarantee that struct pthread is
>            cleared on all architectures.  */
>         THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_UNINITIALIZED);
> +      THREAD_SETMEM (self, rseq_area.cpu_id_start, 0);
>         THREAD_SETMEM (self, rseq_area.rseq_cs, 0);
>         THREAD_SETMEM (self, rseq_area.flags, 0);
>   

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com