On 2019.05.23 06:18:36 +0800, Tina Zhang wrote:

Stack struct intel_gvt_gtt_entry value needs to be initialized before being used, as the fields may contain garbage values.

W/o this patch, set_ggtt_entry prints:

274.046840: set_ggtt_entry: vgpu1:set ggtt entry 0x9bed8000ffffe900 274.046846: set_ggtt_entry: vgpu1:set ggtt entry 0xe55df001 274.046852: set_ggtt_entry: vgpu1:set ggtt entry 0x9bed8000ffffe900

0x9bed8000 is the stack grabage.

W/ this patch, set_ggtt_entry prints:

274.046840: set_ggtt_entry: vgpu1:set ggtt entry 0xffffe900 274.046846: set_ggtt_entry: vgpu1:set ggtt entry 0xe55df001 274.046852: set_ggtt_entry: vgpu1:set ggtt entry 0xffffe900

v2:

• Initialize during declaration. (Zhenyu)

Fixes: 7598e8700e9a(drm/i915/gvt: Missed to cancel dma map for ggtt entries) Cc: stable@vger.kernel.org # v4.20+ Cc: Zhenyu Wang zhenyuw@linux.intel.com Signed-off-by: Tina Zhang tina.zhang@intel.com

---

Will merge this, thanks for the fix!

Reviewed-by: Zhenyu Wang zhenyuw@linux.intel.com

drivers/gpu/drm/i915/gvt/gtt.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 15216c5b40aa..ebc1e5228bf5 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -2179,7 +2179,8 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off, struct intel_gvt_gtt_pte_ops *ops = gvt->gtt.pte_ops; unsigned long g_gtt_index = off >> info->gtt_entry_size_shift; unsigned long gma, gfn;

• struct intel_gvt_gtt_entry e, m;

• struct intel_gvt_gtt_entry e = {.val64 = 0, .type = GTT_TYPE_GGTT_PTE};
• struct intel_gvt_gtt_entry m = {.val64 = 0, .type = GTT_TYPE_GGTT_PTE}; dma_addr_t dma_addr; int ret; struct intel_gvt_partial_pte *partial_pte, *pos, *n;

@@ -2246,7 +2247,8 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off, if (!partial_update && (ops->test_present(&e))) { gfn = ops->get_pfn(&e);

• m = e;
  

• m.val64 = e.val64;
  

• m.type = e.type;
  

/* one PTE update may be issued in multiple writes and the * first write may not construct a valid gfn -- 2.17.1