From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH] x86/hvm: Fix use-after-free introduced by
 c/s 428607a
Date: Tue, 2 Feb 2016 10:48:32 +0000
Message-ID: <56B08980.8060607@citrix.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: Corneliu ZUZU <czuzu@bitdefender.com>, Xen-devel <xen-devel@lists.xen.org>
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On 02/02/16 10:43, Jan Beulich wrote:
>>>> On 01.02.16 at 18:56, <andrew.cooper3@citrix.com> wrote:
>> For safety, NULL out the pointers after freeing them, in an attempt to make
>> mistakes more obvious in the future.
> Except that NULLing isn't really adding that much safety, and we'd
> be better off poisoning such pointers. Nevertheless ...

NULLing the pointers would cause things like rtc_deinit() to always blow
up when it followed the NULL pointer.

IMO, we should unconditionally always NULL pointers when freeing a
pointer which isn't in local scope.  It would make issues such as these
completely obvious.

~Andrew