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BUG: KASAN: use-after-free in tcp_probe_timer net/ipv4/tcp_timer.c:360 [inline]
BUG: KASAN: use-after-free in tcp_write_timer_handler+0x8c6/0x8d0 net/ipv4/tcp_timer.c:596
Read of size 4 at addr ffff88808bfb4610 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.3.0-rc6+ #179
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __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+0x12/0x17 mm/kasan/common.c:618
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
 tcp_probe_timer net/ipv4/tcp_timer.c:360 [inline]
 tcp_write_timer_handler+0x8c6/0x8d0 net/ipv4/tcp_timer.c:596
 tcp_write_timer+0xa8/0x1e0 net/ipv4/tcp_timer.c:612
 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1322
 expire_timers kernel/time/timer.c:1366 [inline]
 __run_timers kernel/time/timer.c:1685 [inline]
 __run_timers kernel/time/timer.c:1653 [inline]
 run_timer_softirq+0x697/0x17a0 kernel/time/timer.c:1698
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:537 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1133
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: e8 b0 6e fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d a4 5b 4a 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 94 5b 4a 00 fb f4 <c3> 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 0e 72 22 fa e8 69
RSP: 0018:ffffffff88c07ce8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11a5e8d RBX: ffffffff88c7a1c0 RCX: 1ffffffff134b61e
RDX: dffffc0000000000 RSI: ffffffff8177f03e RDI: ffffffff873dc4cc
RBP: ffffffff88c07d18 R08: ffffffff88c7a1c0 R09: fffffbfff118f439
R10: fffffbfff118f438 R11: ffffffff88c7a1c7 R12: dffffc0000000000
R13: ffffffff89a57ef8 R14: 0000000000000000 R15: 0000000000000000
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
 default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x413/0x760 kernel/sched/idle.c:263
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:354
 rest_init+0x245/0x37b init/main.c:451
 arch_call_rest_init+0xe/0x1b
 start_kernel+0x912/0x951 init/main.c:785
 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:472
 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:453
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241

Allocated by task 10029:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:493 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:501
 slab_post_alloc_hook mm/slab.h:520 [inline]
 slab_alloc mm/slab.c:3319 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3483
 kmem_cache_zalloc include/linux/slab.h:738 [inline]
 net_alloc net/core/net_namespace.c:410 [inline]
 copy_net_ns+0xf1/0x41f net/core/net_namespace.c:462
 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:2831
 __do_sys_unshare kernel/fork.c:2899 [inline]
 __se_sys_unshare kernel/fork.c:2897 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2897
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2668:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463
 __cache_free mm/slab.c:3425 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3693
 net_free net/core/net_namespace.c:438 [inline]
 net_drop_ns.part.0+0x70/0x90 net/core/net_namespace.c:445
 net_drop_ns net/core/net_namespace.c:444 [inline]
 cleanup_net+0x774/0xa60 net/core/net_namespace.c:613
 process_one_work+0x9af/0x1740 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

The buggy address belongs to the object at ffff88808bfb4040
 which belongs to the cache net_namespace of size 6784
The buggy address is located 1488 bytes inside of
 6784-byte region [ffff88808bfb4040, ffff88808bfb5ac0)
The buggy address belongs to the page:
page:ffffea00022fed00 refcount:1 mapcount:0 mapping:ffff8880a99a6e00 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffff8880a998e948 ffffea00023ade88 ffff8880a99a6e00
raw: 0000000000000000 ffff88808bfb4040 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808bfb4500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808bfb4580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808bfb4600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88808bfb4680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808bfb4700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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