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BUG: KASAN: use-after-free in br_netfilter_sysctl_exit_net net/bridge/br_netfilter_hooks.c:1121 [inline]
BUG: KASAN: use-after-free in brnf_exit_net+0x38c/0x3a0 net/bridge/br_netfilter_hooks.c:1141
Read of size 8 at addr ffff8880946990e0 by task kworker/u4:3/74

CPU: 1 PID: 74 Comm: kworker/u4:3 Not tainted 5.2.0-rc5-next-20190620 #19
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 br_netfilter_sysctl_exit_net net/bridge/br_netfilter_hooks.c:1121 [inline]
 brnf_exit_net+0x38c/0x3a0 net/bridge/br_netfilter_hooks.c:1141
 ops_exit_list.isra.0+0xaa/0x150 net/core/net_namespace.c:165
 cleanup_net+0x4e2/0xa40 net/core/net_namespace.c:575
 process_one_work+0x9af/0x1800 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 16762:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
 __do_kmalloc mm/slab.c:3655 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3664
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:743 [inline]
 __register_sysctl_table+0xc7/0xef0 fs/proc/proc_sysctl.c:1327
 register_net_sysctl+0x29/0x30 net/sysctl_net.c:121
 br_netfilter_sysctl_init_net net/bridge/br_netfilter_hooks.c:1105 [inline]
 brnf_init_net+0x379/0x6a0 net/bridge/br_netfilter_hooks.c:1126
 ops_init+0xb3/0x410 net/core/net_namespace.c:130
 setup_net+0x2e1/0x870 net/core/net_namespace.c:327
 copy_net_ns+0x1df/0x340 net/core/net_namespace.c:456
 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
 ksys_unshare+0x444/0x980 kernel/fork.c:2826
 __do_sys_unshare kernel/fork.c:2894 [inline]
 __se_sys_unshare kernel/fork.c:2892 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2892
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3756
 __rcu_reclaim kernel/rcu/rcu.h:215 [inline]
 rcu_do_batch kernel/rcu/tree.c:2092 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
 rcu_core+0xb5e/0x15a0 kernel/rcu/tree.c:2291
 __do_softirq+0x260/0x9c8 kernel/softirq.c:292

The buggy address belongs to the object at ffff8880946990c0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 32 bytes inside of
 512-byte region [ffff8880946990c0, ffff8880946992c0)
The buggy address belongs to the page:
page:ffffea000251a640 refcount:1 mapcount:0 mapping:ffff8880aa400a80 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000294c1c8 ffffea00018b55c8 ffff8880aa400a80
raw: 0000000000000000 ffff8880946990c0 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888094698f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888094699000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888094699080: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                       ^
 ffff888094699100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888094699180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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