linux-kernel - Re: [PATCH] ptrace: add ability to get clear_tid

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:	Wed, 8 Feb 2012 20:21:26 +0100
From:	Jan Kratochvil <jan.kratochvil@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Pedro Alves <palves@...hat.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Tejun Heo <tj@...nel.org>, Andrew Vagin <avagin@...nvz.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ptrace: add ability to get clear_tid_address

On Wed, 08 Feb 2012 20:02:50 +0100, Oleg Nesterov wrote:
> If only I understood why do we need CLONE_CHILD_SETTID... at least
> I certainly do not understand why glibc translates fork() into
> clone(CLONE_CHILD_SETTID) on my system. The child write into its
> memory, the parent can't see this change. IIRC, initially
> CLONE_CHILD_SETTID wrote child->pid into the parent's memory, and
> even before the child was actually created.

IIUC your question correctly it is because if you PTRACE_SYSCALL SYS_fork
(therefore you PTRACE_SYSCALL SYS_clone) twice (therefore you stop on the
fork/clone syscall exit) you should have struct pthread contents valid for
iterating and examinating the thread structures via libthread_db.

This cannot be achieved by any userland code.


Regards,
Jan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/