[PATCH v2 3/7] drm/amdgpu: Fix the use-after-free issue in wait IOCTL

[Arunpravin Paneer Selvam]

The xarray pointer which has the userqueue xarray structure
reference should be cleared when the userqueue gets
destroyed. Otherwise, we may access the freed xa memory and
see the below warnings.

warning 1:
BUG: KASAN: slab-use-after-free in _raw_spin_lock+0x7a/0xe0
[  +0.000044] Call Trace:
[  +0.000017]  <TASK>
[  +0.000016]  dump_stack_lvl+0x6c/0x90
[  +0.000025]  print_report+0xc4/0x5e0
[  +0.000025]  ? srso_return_thunk+0x5/0x5f
[  +0.000024]  ? kasan_complete_mode_report_info+0x60/0x1d0
[  +0.000030]  ? _raw_spin_lock+0x7a/0xe0
[  +0.000023]  kasan_report+0xdf/0x120
[  +0.000023]  ? _raw_spin_lock+0x7a/0xe0
[  +0.000025]  kasan_check_range+0xf7/0x1b0
[  +0.000025]  __kasan_check_write+0x14/0x20
[  +0.000024]  _raw_spin_lock+0x7a/0xe0
[  +0.000023]  ? __pfx__raw_spin_lock+0x10/0x10
[  +0.000024]  ? amdgpu_userq_wait_ioctl+0xac0/0x1f30 [amdgpu]
[  +0.000442]  amdgpu_userq_wait_ioctl+0x18fc/0x1f30 [amdgpu]
[  +0.000428]  ? __pfx_amdgpu_userq_wait_ioctl+0x10/0x10 [amdgpu]
[  +0.000424]  ? __pfx_idr_alloc_u32+0x10/0x10
[  +0.000027]  ? srso_return_thunk+0x5/0x5f
[  +0.000024]  ? __kasan_check_write+0x14/0x20
[  +0.000025]  ? srso_return_thunk+0x5/0x5f
[  +0.000024]  ? idr_alloc+0x72/0xc0
[  +0.000023]  ? srso_return_thunk+0x5/0x5f
[  +0.000023]  ? fput+0x1c/0x2f0
[  +0.000025]  drm_ioctl_kernel+0x178/0x2f0 [drm]
[  +0.000065]  ? __pfx_amdgpu_userq_wait_ioctl+0x10/0x10 [amdgpu]
[  +0.000425]  ? __pfx_drm_ioctl_kernel+0x10/0x10 [drm]
[  +0.000064]  ? srso_return_thunk+0x5/0x5f
[  +0.000023]  ? __kasan_check_write+0x14/0x20
[  +0.000025]  drm_ioctl+0x513/0xd20 [drm]
[  +0.000058]  ? __pfx_amdgpu_userq_wait_ioctl+0x10/0x10 [amdgpu]
[  +0.000428]  ? __pfx_drm_ioctl+0x10/0x10 [drm]
[  +0.000061]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
[  +0.000027]  ? __count_memcg_events+0x11f/0x3a0
[  +0.000027]  ? srso_return_thunk+0x5/0x5f
[  +0.001040]  ? srso_return_thunk+0x5/0x5f
[  +0.000969]  ? _raw_spin_unlock_irqrestore+0x27/0x50
[  +0.000966]  amdgpu_drm_ioctl+0xcd/0x1d0 [amdgpu]
[  +0.001352]  __x64_sys_ioctl+0x135/0x1b0
[  +0.000966]  x64_sys_call+0x1205/0x20d0
[  +0.000968]  do_syscall_64+0x4d/0x120
[  +0.000960]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  +0.000962] RIP: 0033:0x7f42af11a94f

warning 2:
WARNING: at lib/xarray.c:1849 __xa_alloc+0x13a/0x150
[  366.491409] RIP: 0010:__xa_alloc+0x13a/0x150
[  366.491434] Call Trace:
[  366.491437]  <TASK>
[  366.491440]  ? show_regs+0x6d/0x80
[  366.491445]  ? __warn+0x91/0x140
[  366.491450]  ? __xa_alloc+0x13a/0x150
[  366.491453]  ? report_bug+0x1c9/0x1e0
[  366.491459]  ? handle_bug+0x63/0xa0
[  366.491463]  ? exc_invalid_op+0x1d/0x80
[  366.491467]  ? asm_exc_invalid_op+0x1f/0x30
[  366.491476]  ? __xa_alloc+0x13a/0x150
[  366.491484]  amdgpu_userq_wait_ioctl+0xe0e/0xfe0 [amdgpu]
[  366.491743]  ? idr_alloc_u32+0x97/0xd0
[  366.491749]  ? __pfx_amdgpu_userq_wait_ioctl+0x10/0x10 [amdgpu]
[  366.491912]  drm_ioctl_kernel+0xae/0x100 [drm]
[  366.491942]  drm_ioctl+0x2a1/0x500 [drm]
[  366.491961]  ? __pfx_amdgpu_userq_wait_ioctl+0x10/0x10 [amdgpu]
[  366.492127]  ? srso_return_thunk+0x5/0x5f
[  366.492132]  ? srso_return_thunk+0x5/0x5f
[  366.492135]  ? _raw_spin_unlock_irqrestore+0x2b/0x50
[  366.492139]  amdgpu_drm_ioctl+0x4f/0x90 [amdgpu]
[  366.492288]  __x64_sys_ioctl+0x99/0xd0
[  366.492295]  x64_sys_call+0x1209/0x20d0
[  366.492299]  do_syscall_64+0x51/0x120
[  366.492303]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  366.492418] RIP: 0033:0x7f86f3b1a94f

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c
index cba51bdf2e2c..311d536a7079 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c
@@ -73,6 +73,7 @@ amdgpu_userqueue_cleanup(struct amdgpu_userq_mgr *uq_mgr,
 	}
 
 	uq_funcs->mqd_destroy(uq_mgr, queue);
+	queue->fence_drv->fence_drv_xa_ptr = NULL;
 	amdgpu_userq_fence_driver_free(queue);
 	idr_remove(&uq_mgr->userq_idr, queue_id);
 	kfree(queue);
-- 
2.25.1