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BUG: KASAN: use-after-free in atomic_read /./include/asm-generic/atomic-instrumented.h:26 [inline]
BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x81/0x200 /lib/refcount.c:123
Read of size 4 at addr ffff888097e90680 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0+ #67
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:612
 check_memory_region_inline /mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 /mm/kasan/generic.c:192
 __kasan_check_read+0x11/0x20 /mm/kasan/common.c:92
 atomic_read /./include/asm-generic/atomic-instrumented.h:26 [inline]
 refcount_inc_not_zero_checked+0x81/0x200 /lib/refcount.c:123
 refcount_inc_checked+0x17/0x70 /lib/refcount.c:156
 sock_hold /./include/net/sock.h:649 [inline]
 sk_add_node /./include/net/sock.h:701 [inline]
 nr_insert_socket+0x2d/0xe0 /net/netrom/af_netrom.c:137
 nr_rx_frame+0x1605/0x1e73 /net/netrom/af_netrom.c:1023
 nr_loopback_timer+0x7b/0x170 /net/netrom/nr_loopback.c:59
 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:1095
 apic_timer_interrupt+0xf/0x20 /arch/x86/entry/entry_64.S:828
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 /./arch/x86/include/asm/irqflags.h:61
Code: 68 96 73 fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d e4 26 4f 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d d4 26 4f 00 fb f4 <c3> 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 be 57 27 fa e8 79
RSP: 0018:ffffffff88c07ce8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11a5e05 RBX: ffffffff88c7a1c0 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff88c7aa4c
RBP: ffffffff88c07d18 R08: ffffffff88c7a1c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff89a4f7b8 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:243

Allocated by task 0:
 save_stack+0x23/0x90 /mm/kasan/common.c:69
 set_track /mm/kasan/common.c:77 [inline]
 __kasan_kmalloc /mm/kasan/common.c:487 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 /mm/kasan/common.c:460
 kasan_kmalloc+0x9/0x10 /mm/kasan/common.c:501
 __do_kmalloc /mm/slab.c:3655 [inline]
 __kmalloc+0x163/0x770 /mm/slab.c:3664
 kmalloc /./include/linux/slab.h:557 [inline]
 sk_prot_alloc+0x23a/0x310 /net/core/sock.c:1603
 sk_alloc+0x39/0xf70 /net/core/sock.c:1657
 nr_make_new /net/netrom/af_netrom.c:476 [inline]
 nr_rx_frame+0x733/0x1e73 /net/netrom/af_netrom.c:959
 nr_loopback_timer+0x7b/0x170 /net/netrom/nr_loopback.c:59
 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

Freed by task 9125:
 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:449
 kasan_slab_free+0xe/0x10 /mm/kasan/common.c:457
 __cache_free /mm/slab.c:3425 [inline]
 kfree+0x10a/0x2c0 /mm/slab.c:3756
 sk_prot_free /net/core/sock.c:1640 [inline]
 __sk_destruct+0x4f7/0x6e0 /net/core/sock.c:1726
 sk_destruct+0x86/0xa0 /net/core/sock.c:1734
 __sk_free+0xfb/0x360 /net/core/sock.c:1745
 sk_free+0x42/0x50 /net/core/sock.c:1756
 sock_put /./include/net/sock.h:1725 [inline]
 sock_efree+0x61/0x80 /net/core/sock.c:2042
 skb_release_head_state+0xeb/0x250 /net/core/skbuff.c:652
 skb_release_all+0x16/0x60 /net/core/skbuff.c:663
 __kfree_skb /net/core/skbuff.c:679 [inline]
 kfree_skb /net/core/skbuff.c:697 [inline]
 kfree_skb+0x101/0x3c0 /net/core/skbuff.c:691
 nr_accept+0x56e/0x700 /net/netrom/af_netrom.c:819
 __sys_accept4+0x34e/0x6a0 /net/socket.c:1754
 __do_sys_accept /net/socket.c:1795 [inline]
 __se_sys_accept /net/socket.c:1792 [inline]
 __x64_sys_accept+0x75/0xb0 /net/socket.c:1792
 do_syscall_64+0xfd/0x6a0 /arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888097e90600
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff888097e90600, ffff888097e90e00)
The buggy address belongs to the page:
page:ffffea00025fa400 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002510e08 ffffea0002155b88 ffff8880aa400e00
raw: 0000000000000000 ffff888097e90600 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888097e90580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888097e90600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888097e90680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888097e90700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888097e90780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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