linux-kernel - Re: [PATCH] ptrace: Allow other threads to access tracee

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 11 Mar 2021 16:21:23 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Jim Newsome <jnewsome@...project.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ptrace: Allow other threads to access tracee

On 03/10, Jim Newsome wrote:
>
> @@ -238,7 +238,7 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
>  	 * be changed by us so it's not changing right after this.
>  	 */
>  	read_lock(&tasklist_lock);
> -	if (child->ptrace && child->parent == current) {
> +	if (child->ptrace && same_thread_group(child->parent, current)) {

Cough... it is not that simple.

Just suppose that 2 threads call ptrace(tracee) at the same time. Say, the 1st
thread does PTRACE_CONT while the 2nd thread tries to change the registers.

Oleg.