linux-kernel - Re: [RFC][PATCH] ps command race fix take2 [4/4] proc_pid

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: <p733bbp81p9.fsf@verdi.suse.de>
Date:	22 Aug 2006 13:11:30 +0200
From:	Andi Kleen <ak@...e.de>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Andrew Morton <akpm@...l.org>, ebiederm@...ssion.com, pj@....com,
	saito.tadashi@...t.fujitsu.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] ps command race fix take2 [4/4] proc_pid_readdir

KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> writes:

> proc_pid_readdir() by list_token.
> 
> Remember 'where we are reading' by inserting a token in the list.
> It seems a bit complicated because of RCU but what we do is very simple.
> 

What happens when you have multiple readers at the same time? Can't
the tokens then be mixed up?

>+		/* this small kmalloc() can fail in rare case, but readdir()
>+		 * is not allowed to return ENOMEM. retrying is reasonable. */

Who disallows this? Such retry loops are normally discouraged 
because they can lead to deadlocks in OOM situations.
I think it would be better to just return ENOMEM.

-Andi
-
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/