drm/i915: Avoid dereference past end of page array in gen8_ppgtt_insert_entries()

The bug from gen6_ppgtt_insert_entries() was replicated into
gen8_ppgtt_insert_entries(). This applies the fix for the OOPS from the
previous patch to the gen8 routine.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index de9c945f72a7276dbf2a2cff0b04c6734535409f..8c7ebfa3bd5622cd77716e3580cadeacc8176b42 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -297,23 +297,23 @@ static void gen8_ppgtt_insert_entries(struct i915_address_space *vm,
        unsigned act_pte = first_entry % GEN8_PTES_PER_PAGE;
        struct sg_page_iter sg_iter;
 
-       pt_vaddr = kmap_atomic(&ppgtt->gen8_pt_pages[act_pt]);
+       pt_vaddr = NULL;
        for_each_sg_page(pages->sgl, &sg_iter, pages->nents, 0) {
-               dma_addr_t page_addr;
+               if (pt_vaddr == NULL)
+                       pt_vaddr = kmap_atomic(&ppgtt->gen8_pt_pages[act_pt]);
 
-               page_addr = sg_dma_address(sg_iter.sg) +
-                               (sg_iter.sg_pgoffset << PAGE_SHIFT);
-               pt_vaddr[act_pte] = gen8_pte_encode(page_addr, cache_level,
-                                                   true);
+               pt_vaddr[act_pte] =
+                       gen8_pte_encode(sg_page_iter_dma_address(&sg_iter),
+                                       cache_level, true);
                if (++act_pte == GEN8_PTES_PER_PAGE) {
                        kunmap_atomic(pt_vaddr);
+                       pt_vaddr = NULL;
                        act_pt++;
-                       pt_vaddr = kmap_atomic(&ppgtt->gen8_pt_pages[act_pt]);
                        act_pte = 0;
-
                }
        }
-       kunmap_atomic(pt_vaddr);
+       if (pt_vaddr)
+               kunmap_atomic(pt_vaddr);
 }
 
 static void gen8_ppgtt_cleanup(struct i915_address_space *vm)