linux-kernel - Re: [RFC c/r 4/4] c/r: prctl: Extend PR_SET_MM to set up more mm

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: <CAGXu5jJtBJGt-8iLrC5Jg9N0K2zeYxDtt8uZojY41osejV_aKg@mail.gmail.com>
Date:	Fri, 27 Jan 2012 10:37:05 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Pavel Emelyanov <xemul@...nvz.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Tejun Heo <tj@...nel.org>, Andrew Vagin <avagin@...nvz.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Vasiliy Kulikov <segoon@...nwall.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [RFC c/r 4/4] c/r: prctl: Extend PR_SET_MM to set up more
 mm_struct entries

On Fri, Jan 27, 2012 at 9:53 AM, Cyrill Gorcunov <gorcunov@...nvz.org> wrote:
> +               if (opt == PR_SET_MM_START_STACK)
> +                       mm->start_stack = addr;
> +               else if (opt == PR_SET_MM_ARG_START)
> +                       mm->arg_start = addr;
> +               else if (opt == PR_SET_MM_ARG_END)
> +                       mm->arg_end = addr;
> +               else if (opt == PR_SET_MM_ENV_START)
> +                       mm->env_start = addr;
> +               else if (opt == PR_SET_MM_ENV_END)
> +                       mm->env_end = addr;
> +               break;

Why not a switch statement here? Not that it really matters. :)

> +
> +       case PR_SET_MM_AUXV:
> +               if (arg4 > sizeof(mm->saved_auxv))
> +                       goto out;
> +               up_read(&mm->mmap_sem);
> +
> +               error = -EFAULT;
> +               if (!copy_from_user(mm->saved_auxv, (const void __user *)addr, arg4))
> +                       error = 0;
> +
> +               return error;

Is the mmap_sem released here because of the copy_from_user()? Is it
still safe to write to saved_auxv?

-Kees

-- 
Kees Cook
ChromeOS Security
--
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/