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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 ffff8880603a1280 by task syz-executor.1/12734

CPU: 0 PID: 12734 Comm: syz-executor.1 Not tainted 5.2.0-rc5+ #63
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_read+0x11/0x20 mm/kasan/common.c:94
 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]
 nr_release+0x62/0x3b0 net/netrom/af_netrom.c:520
 __sock_release+0xce/0x2a0 net/socket.c:601
 sock_close+0x1b/0x30 net/socket.c:1273
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 get_signal+0x201b/0x24b0 kernel/signal.c:2434
 do_signal+0x87/0x1900 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459519
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1b21573c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000120
RAX: ffffffffffffff99 RBX: 0000000000000004 RCX: 0000000000459519
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1b215746d4
R13: 00000000004bf4a8 R14: 00000000004d0ba8 R15: 00000000ffffffff

Allocated by task 12743:
 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:3660 [inline]
 __kmalloc+0x15c/0x740 mm/slab.c:3669
 kmalloc include/linux/slab.h:552 [inline]
 sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1599
 sk_alloc+0x39/0xf70 net/core/sock.c:1653
 nr_make_new net/netrom/af_netrom.c:476 [inline]
 nr_rx_frame+0x5d8/0x1d70 net/netrom/af_netrom.c:959
 nr_loopback_timer+0x7b/0x170 net/netrom/nr_loopback.c:59
 call_timer_fn+0x193/0x720 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+0x66f/0x1740 kernel/time/timer.c:1698
 __do_softirq+0x25c/0x94c kernel/softirq.c:292

Freed by task 12734:
 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:3432 [inline]
 kfree+0xcf/0x220 mm/slab.c:3755
 sk_prot_free net/core/sock.c:1636 [inline]
 __sk_destruct+0x4f7/0x6e0 net/core/sock.c:1722
 sk_destruct+0x7b/0x90 net/core/sock.c:1730
 __sk_free+0xce/0x300 net/core/sock.c:1741
 sk_free+0x42/0x50 net/core/sock.c:1752
 sock_put include/net/sock.h:1725 [inline]
 nr_release+0x332/0x3b0 net/netrom/af_netrom.c:554
 __sock_release+0xce/0x2a0 net/socket.c:601
 sock_close+0x1b/0x30 net/socket.c:1273
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 get_signal+0x201b/0x24b0 kernel/signal.c:2434
 do_signal+0x87/0x1900 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880603a1200
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff8880603a1200, ffff8880603a1a00)
The buggy address belongs to the page:
page:ffffea000180e800 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00019d8b08 ffffea0002262008 ffff8880aa400c40
raw: 0000000000000000 ffff8880603a0100 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880603a1180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880603a1200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880603a1280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880603a1300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880603a1380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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