iommu: Fix use-after-free in iommu_release_device

In pci_disable_sriov(), i.e.,

 # echo 0 > /sys/class/net/enp11s0f1np1/device/sriov_numvfs

iommu_release_device
  iommu_group_remove_device
    arm_smmu_domain_free
      kfree(smmu_domain)

Later,

iommu_release_device
  arm_smmu_release_device
    arm_smmu_detach_dev
      spin_lock_irqsave(&smmu_domain->devices_lock,

would trigger an use-after-free. Fixed it by call
arm_smmu_release_device() first before iommu_group_remove_device().

 BUG: KASAN: use-after-free in __lock_acquire+0x3458/0x4440
  __lock_acquire at kernel/locking/lockdep.c:4250
 Read of size 8 at addr ffff0089df1a6f68 by task bash/3356

 CPU: 5 PID: 3356 Comm: bash Not tainted 5.8.0-rc3-next-20200630 #2
 Hardware name: HPE Apollo 70             /C01_APACHE_MB         , BIOS L50_5.13_1.11 06/18/2019
 Call trace:
  dump_backtrace+0x0/0x398
  show_stack+0x14/0x20
  dump_stack+0x140/0x1b8
  print_address_description.isra.12+0x54/0x4a8
  kasan_report+0x134/0x1b8
  __asan_report_load8_noabort+0x2c/0x50
  __lock_acquire+0x3458/0x4440
  lock_acquire+0x204/0xf10
  _raw_spin_lock_irqsave+0xf8/0x180
  arm_smmu_detach_dev+0xd8/0x4a0
  arm_smmu_detach_dev at drivers/iommu/arm-smmu-v3.c:2776
  arm_smmu_release_device+0xb4/0x1c8
  arm_smmu_disable_pasid at drivers/iommu/arm-smmu-v3.c:2754
  (inlined by) arm_smmu_release_device at drivers/iommu/arm-smmu-v3.c:3000
  iommu_release_device+0xc0/0x178
  iommu_release_device at drivers/iommu/iommu.c:302
  iommu_bus_notifier+0x118/0x160
  notifier_call_chain+0xa4/0x128
  __blocking_notifier_call_chain+0x70/0xa8
  blocking_notifier_call_chain+0x14/0x20
  device_del+0x618/0xa00
  pci_remove_bus_device+0x108/0x2d8
  pci_stop_and_remove_bus_device+0x1c/0x28
  pci_iov_remove_virtfn+0x228/0x368
  sriov_disable+0x8c/0x348
  pci_disable_sriov+0x5c/0x70
  mlx5_core_sriov_configure+0xd8/0x260 [mlx5_core]
  sriov_numvfs_store+0x240/0x318
  dev_attr_store+0x38/0x68
  sysfs_kf_write+0xdc/0x128
  kernfs_fop_write+0x23c/0x448
  __vfs_write+0x54/0xe8
  vfs_write+0x124/0x3f0
  ksys_write+0xe8/0x1b8
  __arm64_sys_write+0x68/0x98
  do_el0_svc+0x124/0x220
  el0_sync_handler+0x260/0x408
  el0_sync+0x140/0x180

 Allocated by task 3356:
  save_stack+0x24/0x50
  __kasan_kmalloc.isra.13+0xc4/0xe0
  kasan_kmalloc+0xc/0x18
  kmem_cache_alloc_trace+0x1ec/0x318
  arm_smmu_domain_alloc+0x54/0x148
  iommu_group_alloc_default_domain+0xc0/0x440
  iommu_probe_device+0x1c0/0x308
  iort_iommu_configure+0x434/0x518
  acpi_dma_configure+0xf0/0x128
  pci_dma_configure+0x114/0x160
  really_probe+0x124/0x6d8
  driver_probe_device+0xc4/0x180
  __device_attach_driver+0x184/0x1e8
  bus_for_each_drv+0x114/0x1a0
  __device_attach+0x19c/0x2a8
  device_attach+0x10/0x18
  pci_bus_add_device+0x70/0xf8
  pci_iov_add_virtfn+0x7b4/0xb40
  sriov_enable+0x5c8/0xc30
  pci_enable_sriov+0x64/0x80
  mlx5_core_sriov_configure+0x58/0x260 [mlx5_core]
  sriov_numvfs_store+0x1c0/0x318
  dev_attr_store+0x38/0x68
  sysfs_kf_write+0xdc/0x128
  kernfs_fop_write+0x23c/0x448
  __vfs_write+0x54/0xe8
  vfs_write+0x124/0x3f0
  ksys_write+0xe8/0x1b8
  __arm64_sys_write+0x68/0x98
  do_el0_svc+0x124/0x220
  el0_sync_handler+0x260/0x408
  el0_sync+0x140/0x180

 Freed by task 3356:
  save_stack+0x24/0x50
  __kasan_slab_free+0x124/0x198
  kasan_slab_free+0x10/0x18
  slab_free_freelist_hook+0x110/0x298
  kfree+0x128/0x668
  arm_smmu_domain_free+0xf4/0x1a0
  iommu_group_release+0xec/0x160
  kobject_put+0xf4/0x238
  kobject_del+0x110/0x190
  kobject_put+0x1e4/0x238
  iommu_group_remove_device+0x394/0x938
  iommu_release_device+0x9c/0x178
  iommu_release_device at drivers/iommu/iommu.c:300
  iommu_bus_notifier+0x118/0x160
  notifier_call_chain+0xa4/0x128
  __blocking_notifier_call_chain+0x70/0xa8
  blocking_notifier_call_chain+0x14/0x20
  device_del+0x618/0xa00
  pci_remove_bus_device+0x108/0x2d8
  pci_stop_and_remove_bus_device+0x1c/0x28
  pci_iov_remove_virtfn+0x228/0x368
  sriov_disable+0x8c/0x348
  pci_disable_sriov+0x5c/0x70
  mlx5_core_sriov_configure+0xd8/0x260 [mlx5_core]
  sriov_numvfs_store+0x240/0x318
  dev_attr_store+0x38/0x68
  sysfs_kf_write+0xdc/0x128
  kernfs_fop_write+0x23c/0x448
  __vfs_write+0x54/0xe8
  vfs_write+0x124/0x3f0
  ksys_write+0xe8/0x1b8
  __arm64_sys_write+0x68/0x98
  do_el0_svc+0x124/0x220
  el0_sync_handler+0x260/0x408
  el0_sync+0x140/0x180

 The buggy address belongs to the object at ffff0089df1a6e00
  which belongs to the cache kmalloc-512 of size 512
 The buggy address is located 360 bytes inside of
  512-byte region [ffff0089df1a6e00, ffff0089df1a7000)
 The buggy address belongs to the page:
 page:ffffffe02257c680 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0089df1a1400
 flags: 0x7ffff800000200(slab)
 raw: 007ffff800000200 ffffffe02246b8c8 ffffffe02257ff88 ffff000000320680
 raw: ffff0089df1a1400 00000000002a000e 00000001ffffffff ffff0089df1a5001
 page dumped because: kasan: bad access detected
 page->mem_cgroup:ffff0089df1a5001

 Memory state around the buggy address:
  ffff0089df1a6e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff0089df1a6e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 >ffff0089df1a6f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                           ^
  ffff0089df1a6f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff0089df1a7000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Fixes: a6a4c7e2c5 ("iommu: Add probe_device() and release_device() call-backs")
Signed-off-by: Qian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/20200704001003.2303-1-cai@lca.pw
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -295,10 +295,10 @@ void iommu_release_device(struct device *dev)
 		return;
 
 	iommu_device_unlink(dev->iommu->iommu_dev, dev);
-	iommu_group_remove_device(dev);
 
 	ops->release_device(dev);
 
+	iommu_group_remove_device(dev);
 	module_put(ops->owner);
 	dev_iommu_free(dev);
 }