linux-kernel - Re: [PATCH 2/2] ptrace: do not use task

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:	Mon,  4 May 2009 12:09:35 -0700 (PDT)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Jeff Dike <jdike@...toit.com>, utrace-devel@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ptrace: do not use task_lock() for attach

This looks good to me overall.  It might be worth slicing it into two or
more patches, just for bisect paranoia.  (e.g. PF_KTHREAD; task_lock in
ptrace_attach; task_lock in ptrace_traceme.)

I think it merits a comment that the PF_KTHREAD check does not need any
interlock because daemonize() will detach ptrace via reparent_to_kthreadd()
after it sets PF_KTHREAD.  (vs the old ->mm check under task_lock.)

It is worth noting that this changes the security_ptrace_traceme() call so
it's no longer under task_lock().  I can't see any way the LSM hooks care,
but it is a change.

You also didn't mention the s/|=/=/ changes.  Those are correct, we've
already agreed, but the commit log should mention that this subtle change
was intentional.

Thanks,
Roland
--
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/