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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2019-04-04 08:30:56 +0100 |
|---|---|---|
| committer | Zhenyu Wang <zhenyuw@linux.intel.com> | 2019-04-08 10:39:52 +0800 |
| commit | 968a85b19d0a79dd8ed85f39e23eacd34b503e72 (patch) | |
| tree | 0646dc5cd4c6a889be8a9b4c2160f92bea33f44d | |
| parent | 196a66275520ffc27513c56ecc06a2d9450fd12f (diff) | |
| download | fscrypt-968a85b19d0a79dd8ed85f39e23eacd34b503e72.tar.gz | |
drm/i915/gvt: Prevent use-after-free in ppgtt_free_all_spt()
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")
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
| -rw-r--r-- | drivers/gpu/drm/i915/gvt/gtt.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index cf133ef038735d..9814773882ec2b 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( |