==================================================================
BUG: KASAN: use-after-free in devlink_health_reporter_destroy+0x184/0x1d0 net/core/devlink.c:5476
Read of size 8 at addr ffff888097a13020 by task kworker/u4:4/262
CPU: 0 PID: 262 Comm: kworker/u4:4 Not tainted 5.8.0-rc4-next-20200713-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 devlink_health_reporter_destroy+0x184/0x1d0 net/core/devlink.c:5476
 nsim_dev_health_exit+0x8b/0xe0 drivers/net/netdevsim/health.c:317
 nsim_dev_reload_destroy+0x132/0x1e0 drivers/net/netdevsim/dev.c:1134
 nsim_dev_reload_down+0x6e/0xd0 drivers/net/netdevsim/dev.c:712
 devlink_reload+0xc1/0x3a0 net/core/devlink.c:2952
 devlink_pernet_pre_exit+0xfb/0x190 net/core/devlink.c:9622
 ops_pre_exit_list net/core/net_namespace.c:176 [inline]
 cleanup_net+0x451/0xa00 net/core/net_namespace.c:591
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Allocated by task 6833:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 kmem_cache_alloc_trace+0x16e/0x2c0 mm/slab.c:3550
 kmalloc include/linux/slab.h:554 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 __devlink_health_reporter_create+0x91/0x2f0 net/core/devlink.c:5359
 devlink_health_reporter_create+0xa1/0x1d0 net/core/devlink.c:5431
 nsim_dev_health_init+0x95/0x3a0 drivers/net/netdevsim/health.c:279
 nsim_dev_probe+0xada/0xf80 drivers/net/netdevsim/dev.c:1086
 really_probe+0x282/0x9f0 drivers/base/dd.c:531
 driver_probe_device+0xfe/0x1d0 drivers/base/dd.c:716
 __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:822
 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431
 __device_attach+0x28d/0x3f0 drivers/base/dd.c:888
 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
 device_add+0xb17/0x1c40 drivers/base/core.c:2921
 nsim_bus_dev_new drivers/net/netdevsim/bus.c:336 [inline]
 new_device_store+0x374/0x5c0 drivers/net/netdevsim/bus.c:215
 bus_attr_store+0x72/0xa0 drivers/base/bus.c:122
 sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:138
 kernfs_fop_write+0x268/0x490 fs/kernfs/file.c:315
 vfs_write+0x2b0/0x6b0 fs/read_write.c:593
 ksys_write+0x12d/0x250 fs/read_write.c:648
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Freed by task 262:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3418 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3756
 devlink_health_reporter_free net/core/devlink.c:5449 [inline]
 devlink_health_reporter_put+0xb7/0xf0 net/core/devlink.c:5456
 __devlink_health_reporter_destroy net/core/devlink.c:5463 [inline]
 devlink_health_reporter_destroy+0x143/0x1d0 net/core/devlink.c:5475
 nsim_dev_health_exit+0x8b/0xe0 drivers/net/netdevsim/health.c:317
 nsim_dev_reload_destroy+0x132/0x1e0 drivers/net/netdevsim/dev.c:1134
 nsim_dev_reload_down+0x6e/0xd0 drivers/net/netdevsim/dev.c:712
 devlink_reload+0xc1/0x3a0 net/core/devlink.c:2952
 devlink_pernet_pre_exit+0xfb/0x190 net/core/devlink.c:9622
 ops_pre_exit_list net/core/net_namespace.c:176 [inline]
 cleanup_net+0x451/0xa00 net/core/net_namespace.c:591
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
The buggy address belongs to the object at ffff888097a13000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 32 bytes inside of
 512-byte region [ffff888097a13000, ffff888097a13200)
The buggy address belongs to the page:
page:0000000006bc1d4a refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888097a13c00 pfn:0x97a13
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002533e88 ffffea0002a1c208 ffff8880aa000600
raw: ffff888097a13c00 ffff888097a13000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
 ffff888097a12f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888097a12f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888097a13000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888097a13080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888097a13100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================