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Subject[PATCH] drm/i915/gvt: fix double free bug in split_2MB_gtt_entry
Date
If intel_gvt_dma_map_guest_page failed, it will call
ppgtt_invalidate_spt, which will finally free the spt.
But the caller does not notice that, it will free spt again in error path.

Fix this by only freeing spt in ppgtt_invalidate_spt in good case.

Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support")
Reported-by: Zheng Wang <hackerzheng666@gmail.com>
Signed-off-by: Zheng Wang <zyytlz.wz@163.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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