Re: [PATCH 1/2] x86/uprobes: Keep shadow stack in sync for emulated CALLs

[Oleg Nesterov <oleg@redhat.com>]

On 06/22, David Windsor wrote:
>
> --- a/arch/x86/kernel/uprobes.c
> +++ b/arch/x86/kernel/uprobes.c
> @@ -1246,8 +1246,12 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
>  		long correction = utask->vaddr - utask->xol_vaddr;
>  		regs->ip += correction;
>  	} else if (auprobe->defparam.fixups & UPROBE_FIX_CALL) {
> +		unsigned long retaddr = utask->vaddr + auprobe->defparam.ilen;
> +
>  		regs->sp += sizeof_long(regs); /* Pop incorrect return address */
> -		if (emulate_push_stack(regs, utask->vaddr + auprobe->defparam.ilen))
> +		if (emulate_push_stack(regs, retaddr))
> +			return -ERESTART;
> +		if (shstk_update_last_frame(retaddr))
>  			return -ERESTART;

Well, if shstk_update_last_frame() fails after emulate_push_stack(), we should
probably return another error, so that the caller handle_singlestep() will kill
this task?

Oleg.