linux-kernel - Re: [PATCH] user_ns: use correct check for single-threadedness

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 for Android: free password hash cracker in your pocket

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

Date:	Tue, 28 Jul 2015 14:02:18 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Kees Cook <keescook@...omium.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Oleg Nesterov <oleg@...hat.com>,
	David Howells <dhowells@...hat.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Vladimir Davydov <vdavydov@...allels.com>,
	Ricky Zhou <rickyz@...omium.org>,
	Julien Tinnes <jln@...gle.com>
Subject: Re: [PATCH] user_ns: use correct check for single-threadedness

On 07/28/2015 01:15 PM, Kees Cook wrote:
> From: Ricky Zhou <rickyz@...omium.org>
> 
> Checking mm_users > 1 does not mean a process is multithreaded. For
> example, reading /proc/PID/maps temporarily increments mm_users, allowing
> other processes to (accidentally) interfere with unshare() calls.
> 
> This fixes observed failures of unshare(CLONE_NEWUSER) incorrectly
> returning EINVAL if another processes happened to be simultaneously
> reading the maps file.
> 
> Signed-off-by: Ricky Zhou <rickyz@...omium.org>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> Cc: stable@...r.kernel.org

Reviewed-by: Rik van Riel <riel@...hat.com>

--
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/