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From: Ingo Molnar <mingo@elte.hu>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>,
	Vasiliy Kulikov <segoon@openwall.com>,
	Dan Ballard <dan@mindstab.net>, Jiri Kosina <jkosina@suse.cz>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Stephen Wilson <wilsons@start.ca>,
	David Rientjes <rientjes@google.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Eric Paris <eparis@redhat.com>,
	"Serge E. Hallyn" <serge.hallyn@canonical.com>,
	linux-doc@vger.kernel.org
Subject: Re: [PATCH] sysctl: control functionality of /proc/pid/mem
Date: Sat, 21 Jan 2012 10:03:42 +0100	[thread overview]
Message-ID: <20120121090342.GD32134@elte.hu> (raw)
In-Reply-To: <20120121084317.GA30541@www.outflux.net>


* Kees Cook <keescook@chromium.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.

See how easy it is to introduce bugs with potential security 
side-effects, even when the intention is to increase security?
:-)

( Btw., this is why i generally prefer 'invariant' local
  variable definition blocks that have no serious side effects -
  it makes the flow more obvious. Local variables slip off the 
  eye rather often and don't register as 'real' code.)

Thanks,

	Ingo

  reply	other threads:[~2012-01-21  9:04 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-21  8:43 [PATCH] sysctl: control functionality of /proc/pid/mem Kees Cook
2012-01-21  9:03 ` Ingo Molnar [this message]
2012-01-21  9:11   ` Kees Cook

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