All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] drm/i915/gvt: Prevent use-after-free in ppgtt_free_all_spt()
@ 2019-04-04  7:30 Chris Wilson
  2019-04-04  7:48 ` Zhenyu Wang
                   ` (3 more replies)
  0 siblings, 4 replies; 7+ messages in thread
From: Chris Wilson @ 2019-04-04  7:30 UTC (permalink / raw)
  To: intel-gfx; +Cc: Changbin Du, intel-gvt-dev

ppgtt_free_all_spt() iterates the radixtree as it is deleting it,
forgoing all protection against the leaves being freed in the process
(leaving the iter pointing into the void).

A minimal fix seems to be to use the available post_shadow_list to
decompose the tree into a list prior to destroying the radixtree.

Alerted by the sparse warnings:

drivers/gpu/drm/i915/gvt/gtt.c:757:9: warning: incorrect type in assignment (different address spaces)
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    expected void **slot
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    got void [noderef] <asn:4> **
drivers/gpu/drm/i915/gvt/gtt.c:757:9: warning: incorrect type in assignment (different address spaces)
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    expected void **slot
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    got void [noderef] <asn:4> **
drivers/gpu/drm/i915/gvt/gtt.c:758:45: warning: incorrect type in argument 1 (different address spaces)
drivers/gpu/drm/i915/gvt/gtt.c:758:45:    expected void [noderef] <asn:4> **slot
drivers/gpu/drm/i915/gvt/gtt.c:758:45:    got void **slot
drivers/gpu/drm/i915/gvt/gtt.c:757:9: warning: incorrect type in argument 1 (different address spaces)
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    expected void [noderef] <asn:4> **slot
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    got void **slot
drivers/gpu/drm/i915/gvt/gtt.c:757:9: warning: incorrect type in assignment (different address spaces)
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    expected void **slot
drivers/gpu/drm/i915/gvt/gtt.c:757:9:    got void [noderef] <asn:4> **

This would also have been loudly warning if run through CI for the
invalid RCU dereferences.

Fixes: b6c126a39345 ("drm/i915/gvt: Manage shadow pages with radix tree")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index cf133ef03873..9814773882ec 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -750,14 +750,20 @@ static void ppgtt_free_spt(struct intel_vgpu_ppgtt_spt *spt)
 
 static void ppgtt_free_all_spt(struct intel_vgpu *vgpu)
 {
-	struct intel_vgpu_ppgtt_spt *spt;
+	struct intel_vgpu_ppgtt_spt *spt, *spn;
 	struct radix_tree_iter iter;
-	void **slot;
+	LIST_HEAD(all_spt);
+	void __rcu **slot;
 
+	rcu_read_lock();
 	radix_tree_for_each_slot(slot, &vgpu->gtt.spt_tree, &iter, 0) {
 		spt = radix_tree_deref_slot(slot);
-		ppgtt_free_spt(spt);
+		list_move(&spt->post_shadow_list, &all_spt);
 	}
+	rcu_read_unlock();
+
+	list_for_each_entry_safe(spt, spn, &all_spt, post_shadow_list)
+		ppgtt_free_spt(spt);
 }
 
 static int ppgtt_handle_guest_write_page_table_bytes(
-- 
2.20.1

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply related	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-04-08  2:27 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-04-04  7:30 [PATCH] drm/i915/gvt: Prevent use-after-free in ppgtt_free_all_spt() Chris Wilson
2019-04-04  7:48 ` Zhenyu Wang
2019-04-04  8:11   ` Chris Wilson
2019-04-08  2:27     ` Zhenyu Wang
2019-04-04  8:07 ` ✗ Fi.CI.SPARSE: warning for " Patchwork
2019-04-04  8:25 ` ✓ Fi.CI.BAT: success " Patchwork
2019-04-04 22:33 ` ✓ Fi.CI.IGT: " Patchwork

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.