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Message-ID: <CAJedcCzt_1ZRV5egMLdoFVZ4hBDE+nDu9fLkBuGY0A=uYicvQA@mail.gmail.com>
Date: Fri, 16 Sep 2022 23:54:42 +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.
>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,
ops->get_pfn(e));
return -ENXIO;
}
- return ppgtt_invalidate_spt(s);
+ return ppgtt_invalidate_spt(s, 0);
}
static inline void ppgtt_invalidate_pte(struct intel_vgpu_ppgtt_spt *spt,
@@ -1016,7 +1016,7 @@ static inline void ppgtt_invalidate_pte(struct
intel_vgpu_ppgtt_spt *spt,
intel_gvt_dma_unmap_guest_page(vgpu, pfn << PAGE_SHIFT);
}
-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)
{
struct intel_vgpu *vgpu = spt->vgpu;
struct intel_gvt_gtt_entry e;
@@ -1059,9 +1059,11 @@ static int ppgtt_invalidate_spt(struct
intel_vgpu_ppgtt_spt *spt)
}
}
- trace_spt_change(spt->vgpu->id, "release", spt,
+ if (!is_error) {
+ trace_spt_change(spt->vgpu->id, "release", spt,
spt->guest_page.gfn, spt->shadow_page.type);
- ppgtt_free_spt(spt);
+ ppgtt_free_spt(spt);
+ }
return 0;
fail:
gvt_vgpu_err("fail: shadow page %p shadow entry 0x%llx type %d\n",
@@ -1215,7 +1217,7 @@ static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,
ret = intel_gvt_dma_map_guest_page(vgpu, start_gfn + sub_index,
PAGE_SIZE, &dma_addr);
if (ret) {
- ppgtt_invalidate_spt(spt);
+ ppgtt_invalidate_spt(spt, 1);
return ret;
}
sub_se.val64 = se->val64;
@@ -1393,7 +1395,7 @@ static int
ppgtt_handle_guest_entry_removal(struct intel_vgpu_ppgtt_spt *spt,
ret = -ENXIO;
goto fail;
}
- ret = ppgtt_invalidate_spt(s);
+ ret = ppgtt_invalidate_spt(s, 0);
if (ret)
goto fail;
} else {
--
2.25.1
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