From 83967c57320d0d01ae512f10e79213f81e4bf594 Mon Sep 17 00:00:00 2001
From: Matthew Auld <matthew.auld@intel.com>
Date: Fri, 12 Apr 2024 12:31:45 +0100
Subject: [PATCH] drm/xe/vm: prevent UAF with asid based lookup
The asid is only erased from the xarray when the vm refcount reaches
zero, however this leads to potential UAF since the xe_vm_get() only
works on a vm with refcount != 0. Since the asid is allocated in the vm
create ioctl, rather erase it when closing the vm, prior to dropping the
potential last ref. This should also work when user closes driver fd
without explicit vm destroy.
Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1594
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412113144.259426-4-matthew.auld@intel.com
---
drivers/gpu/drm/xe/xe_vm.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index 2dbba55e7785..b31e263ca754 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -1481,6 +1481,16 @@ void xe_vm_close_and_put(struct xe_vm *vm)
xe->usm.num_vm_in_fault_mode--;
else if (!(vm->flags & XE_VM_FLAG_MIGRATION))
xe->usm.num_vm_in_non_fault_mode--;
+
+ if (vm->usm.asid) {
+ void *lookup;
+
+ xe_assert(xe, xe->info.has_asid);
+ xe_assert(xe, !(vm->flags & XE_VM_FLAG_MIGRATION));
+
+ lookup = xa_erase(&xe->usm.asid_to_vm, vm->usm.asid);
+ xe_assert(xe, lookup == vm);
+ }
mutex_unlock(&xe->usm.lock);
for_each_tile(tile, xe, id)
@@ -1496,24 +1506,15 @@ static void vm_destroy_work_func(struct work_struct *w)
struct xe_device *xe = vm->xe;
struct xe_tile *tile;
u8 id;
- void *lookup;
/* xe_vm_close_and_put was not called? */
xe_assert(xe, !vm->size);
mutex_destroy(&vm->snap_mutex);
- if (!(vm->flags & XE_VM_FLAG_MIGRATION)) {
+ if (!(vm->flags & XE_VM_FLAG_MIGRATION))
xe_device_mem_access_put(xe);
- if (xe->info.has_asid && vm->usm.asid) {
- mutex_lock(&xe->usm.lock);
- lookup = xa_erase(&xe->usm.asid_to_vm, vm->usm.asid);
- xe_assert(xe, lookup == vm);
- mutex_unlock(&xe->usm.lock);
- }
- }
-
for_each_tile(tile, xe, id)
XE_WARN_ON(vm->pt_root[id]);
--
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