Commit 787ef0db authored Dec 30, 2022 by Zheng Wang Committed by Greg Kroah-Hartman Feb 25, 2023

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



commit 4a61648af68f5ba4884f0e3b494ee1cabc4b6620 upstream.

If intel_gvt_dma_map_guest_page failed, it will call
ppgtt_invalidate_spt, which will finally free the spt.
But the caller function ppgtt_populate_spt_by_guest_entry
does not notice that, it will free spt again in its error
path.

Fix this by canceling the mapping of DMA address and freeing sub_spt.
Besides, leave the handle of spt destroy to caller function instead
of callee function when error occurs.

Fixes: b901b252 ("drm/i915/gvt: Add 2M huge gtt support")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20221229165641.1192455-1-zyytlz.wz@163.com


Signed-off-by: Ovidiu Panait <ovidiu.panait@eng.windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 100cf2af

drivers/gpu/drm/i915/gvt/gtt.c

+13 −4

Original line number	Diff line number	Diff line
		@@ -1186,10 +1186,8 @@ static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,
		for_each_shadow_entry(sub_spt, &sub_se, sub_index) {
		ret = intel_gvt_hypervisor_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. */
		@@ -1208,6 +1206,17 @@ 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,