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Message-ID: <CAJedcCwzgELQquRLc2deXt+E4X2D2-NMLERpE1z3sy21bTdddw@mail.gmail.com>
Date: Mon, 19 Sep 2022 01:17:59 +0800
From: Zheng Hacker <hackerzheng666@...il.com>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: Zhenyu Wang <zhenyuw@...ux.intel.com>,
"alex000young@...il.com" <alex000young@...il.com>,
"security@...nel.org" <security@...nel.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"tvrtko.ursulin@...ux.intel.com" <tvrtko.ursulin@...ux.intel.com>,
"airlied@...ux.ie" <airlied@...ux.ie>,
"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
"joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
xmzyshypnc <1002992920@...com>,
"jani.nikula@...ux.intel.com" <jani.nikula@...ux.intel.com>,
"daniel@...ll.ch" <daniel@...ll.ch>,
"rodrigo.vivi@...el.com" <rodrigo.vivi@...el.com>,
"intel-gvt-dev@...ts.freedesktop.org"
<intel-gvt-dev@...ts.freedesktop.org>,
"zhi.a.wang@...el.com" <zhi.a.wang@...el.com>
Subject: Re: [PATCH] drm/i915/gvt: fix double-free bug in split_2MB_gtt_entry.
I'll try using another mail client like Mutt later. :)
Regards,
Zheng Wang
Greg KH <gregkh@...uxfoundation.org> 于2022年9月17日周六 17:07写道:
>
> On Fri, Sep 16, 2022 at 11:54:42PM +0800, Zheng Hacker wrote:
> > >From afe79848cb74cc8e45ab426d13fa2394c87e0422 Mon Sep 17 00:00:00 2001
> > From: xmzyshypnc <1002992920@...com>
> > Date: Fri, 16 Sep 2022 23:48:23 +0800
> > Subject: [PATCH] drm/i915/gvt: fix double-free bug in split_2MB_gtt_entry
> >
> > There is a double-free security bug in split_2MB_gtt_entry.
> >
> > Here is a calling chain :
> > ppgtt_populate_spt->ppgtt_populate_shadow_entry->split_2MB_gtt_entry.
> >
> > If intel_gvt_dma_map_guest_page failed, it will call
> > ppgtt_invalidate_spt, which will finally call ppgtt_free_spt and
> > kfree(spt). But the caller does not notice that, and it will call
> > ppgtt_free_spt again in error path.
> >
> > Fix this by only freeing spt in ppgtt_invalidate_spt in good case.
> >
> > Signed-off-by: Zheng Wang <hackerzheng666@...il.com>
> > ---
> > drivers/gpu/drm/i915/gvt/gtt.c | 16 +++++++++-------
> > 1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> > index ce0eb03709c3..550519f0acca 100644
> > --- a/drivers/gpu/drm/i915/gvt/gtt.c
> > +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> > @@ -959,7 +959,7 @@ static inline int ppgtt_put_spt(struct
> > intel_vgpu_ppgtt_spt *spt)
> > return atomic_dec_return(&spt->refcount);
> > }
> >
> > -static int ppgtt_invalidate_spt(struct intel_vgpu_ppgtt_spt *spt);
> > +static int ppgtt_invalidate_spt(struct intel_vgpu_ppgtt_spt *spt, int
> > is_error);
> >
> > static int ppgtt_invalidate_spt_by_shadow_entry(struct intel_vgpu *vgpu,
> > struct intel_gvt_gtt_entry *e)
> > @@ -995,7 +995,7 @@ static int
> > ppgtt_invalidate_spt_by_shadow_entry(struct intel_vgpu *vgpu,
>
> Still line-wrapped and whitespace broken :(
>
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