linux-kernel - Re: [PATCH] sysctl: control functionality of /proc/pid/mem

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Message-ID: <CAGXu5jJoLB-hBUpYtBS78MmDbm0Xc7QykmBDb15tt22crydB5w@mail.gmail.com>
Date:	Sat, 21 Jan 2012 01:11:01 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Randy Dunlap <rdunlap@...otime.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Vasiliy Kulikov <segoon@...nwall.com>,
	Dan Ballard <dan@...dstab.net>, Jiri Kosina <jkosina@...e.cz>,
	Al Viro <viro@...iv.linux.org.uk>,
	Stephen Wilson <wilsons@...rt.ca>,
	David Rientjes <rientjes@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Eric Paris <eparis@...hat.com>,
	"Serge E. Hallyn" <serge.hallyn@...onical.com>,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH] sysctl: control functionality of /proc/pid/mem

On Sat, Jan 21, 2012 at 1:03 AM, Ingo Molnar <mingo@...e.hu> wrote:
> * Kees Cook <keescook@...omium.org> wrote:
>
>> @@ -702,6 +704,9 @@ static int mem_open(struct inode* inode, struct file* file)
>>       struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
>>       struct mm_struct *mm;
>>
>> +     if (sysctl_proc_pid_mem < 1)
>> +             return -EACCES;
>
> This looks like an unprivileged user-space triggerable memory
> leak DoS. The task reference is already acquired at that point.

Ah, good catch; thanks. I'll respin.

-Kees

-- 
Kees Cook
ChromeOS Security
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