drm/i915/gvt: fix double free bug in split_2MB_gtt_entry

From Zheng Wang
1022519da69d99d455c58ca181a6c499c562c70e in linux-6.1.y/6.1.5
4a61648af68f5ba4884f0e3b494ee1cabc4b6620 in mainline linux

diff --git a/sys/dev/pci/drm/i915/gvt/gtt.c b/sys/dev/pci/drm/i915/gvt/gtt.c
index a956b53..b49d16e 100644 (file)
--- a/sys/dev/pci/drm/i915/gvt/gtt.c
+++ b/sys/dev/pci/drm/i915/gvt/gtt.c
@@ -1214,10 +1214,8 @@ static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,
        for_each_shadow_entry(sub_spt, &sub_se, sub_index) {
                ret = intel_gvt_dma_map_guest_page(vgpu, start_gfn + sub_index,
                                                   PAGE_SIZE, &dma_addr);
-               if (ret) {
-                       ppgtt_invalidate_spt(spt);
-                       return ret;
-               }
+               if (ret)
+                       goto err;
                sub_se.val64 = se->val64;
 
                /* Copy the PAT field from PDE. */
@@ -1236,6 +1234,17 @@ static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,
        ops->set_pfn(se, sub_spt->shadow_page.mfn);
        ppgtt_set_shadow_entry(spt, se, index);
        return 0;
+err:
+       /* Cancel the existing addess mappings of DMA addr. */
+       for_each_present_shadow_entry(sub_spt, &sub_se, sub_index) {
+               gvt_vdbg_mm("invalidate 4K entry\n");
+               ppgtt_invalidate_pte(sub_spt, &sub_se);
+       }
+       /* Release the new allocated spt. */
+       trace_spt_change(sub_spt->vgpu->id, "release", sub_spt,
+               sub_spt->guest_page.gfn, sub_spt->shadow_page.type);
+       ppgtt_free_spt(sub_spt);
+       return ret;
 }
 
 static int split_64KB_gtt_entry(struct intel_vgpu *vgpu,