[PATCH 1/2] ptrace: PTRACE_SET_SYSCALL_INFO syscall skipping support

[Oleg Nesterov]

On 07/04, Renzo Davoli wrote:
>
> -	/* Changing the type of the system call stop is not supported yet. */
> -	if (ptrace_get_syscall_info_op(child) != info.op)
> -		return -EINVAL;
> +	/*
> +	 * Changing the type of the system call stop is not allowed, with the
> +	 * following exception:
> +	 * PTRACE_SYSCALL_INFO_SECCOMP or PTRACE_SYSCALL_INFO_ENTRY can be changed
> +	 * to PTRACE_SYSCALL_INFO_EXIT to skip the system call
> +	 */
> +
> +	if (ptrace_get_syscall_info_op(child) != info.op) {
> +		if (info.op != PTRACE_SYSCALL_INFO_EXIT)
> +			return -EINVAL;
> +		skip_syscall = true;
> +	}

Ah... I forgot that ptrace_get_syscall_info_op() can return _NONE.

We should not allow _NONE -> _EXIT transition.

Oleg.