linux-kernel - Re: [patch 3/14] x86, ptrace, bts: stop bts tracing early in do

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]

Message-ID: <20090327143435.GD14504@redhat.com>
Date:	Fri, 27 Mar 2009 15:34:35 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Markus Metzger <markus.t.metzger@...el.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, tglx@...utronix.de,
	hpa@...or.com, markus.t.metzger@...il.com, roland@...hat.com,
	eranian@...glemail.com, juan.villacis@...el.com,
	ak@...ux.jf.intel.com
Subject: Re: [patch 3/14] x86, ptrace, bts: stop bts tracing early in
	do_exit

On 03/27, Markus Metzger wrote:
>
> +static void ptrace_bts_exit(void)
> +{
> +	if (unlikely(!list_empty(&current->ptraced)))
> +		ptrace_bts_exit_tracer();
> +
> +	if (unlikely(current->bts))
> +		ptrace_bts_exit_tracee();
> +}

Could you explain why do we need ptrace_bts_exit_tracee() ?

If current is traced, the tracer should do ptrace_bts_release()
eventually, no?

And if we really need to do ptrace_bts_exit_tracee(), then
"if (unlikely(current->bts))" check is racy. The tracer
can do PTRACE_BTS_CONFIG right after the check.

Oleg.

--
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/