From: Borislav Petkov <bp@amd64.org>
To: kernel-janitors@vger.kernel.org
Subject: Re: [patch] x86, microcode, AMD: use after free in free_cache()
Date: Thu, 06 Sep 2012 12:01:45 +0000 [thread overview]
Message-ID: <20120906120145.GA550@aftab.osrc.amd.com> (raw)
In-Reply-To: <20120905123042.GB6128@elgon.mountain>
On Wed, Sep 05, 2012 at 04:42:03PM -0700, Dan Carpenter wrote:
> The dereference happens inside the assignment.
Yes, this:
#define list_for_each_entry_reverse(pos, head, member) \
for (pos = list_entry((head)->prev, typeof(*pos), member); \
&pos->member != (head); \ <--- DEREF.
pos = list_entry(pos->member.prev, typeof(*pos), member))
but we kfree pos aka p after the deref and in the next iteration p
becomes the list entry of the next list element, AFAICT.
> That's actually the reason why we have the the _safe() version of the
> macro.
_safe, the way I see it, is for concurrent list manipulations and at the
point we free the cache, I don't see us concurrently manipulating that
list.
So, sorry, but I don't see the problem.
--
Regards/Gruss,
Boris.
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
next prev parent reply other threads:[~2012-09-06 12:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 12:30 [patch] x86, microcode, AMD: use after free in free_cache() Dan Carpenter
2012-09-05 13:20 ` Borislav Petkov
2012-09-05 23:42 ` Dan Carpenter
2012-09-06 12:01 ` Borislav Petkov [this message]
2012-09-06 12:30 ` Dan Carpenter
2012-09-06 13:06 ` Borislav Petkov
2012-09-06 14:04 ` Dan Carpenter
2012-09-06 16:16 ` Borislav Petkov
2012-09-12 11:00 ` Borislav Petkov
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