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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+0x7c/0x280 lib/refcount.c:123
Read of size 4 at addr ffff8880971b4500 by task syz-executor.3/757

CPU: 1 PID: 757 Comm: syz-executor.3 Not tainted 5.3.0-rc2+ #61
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+0x1d8/0x2f8 lib/dump_stack.c:113
 print_address_description+0x75/0x5b0 mm/kasan/report.c:351
 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:482
 kasan_report+0x26/0x50 mm/kasan/common.c:612
 check_memory_region_inline mm/kasan/generic.c:182 [inline]
 check_memory_region+0x2cf/0x2e0 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+0x7c/0x280 lib/refcount.c:123
 refcount_inc_checked+0x15/0x50 lib/refcount.c:156
 sock_hold include/net/sock.h:649 [inline]
 nr_release+0x59/0x390 net/netrom/af_netrom.c:520
 __sock_release net/socket.c:590 [inline]
 sock_close+0xe1/0x260 net/socket.c:1268
 __fput+0x2e4/0x740 fs/file_table.c:280
 ____fput+0x15/0x20 fs/file_table.c:313
 task_work_run+0x17e/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
 prepare_exit_to_usermode+0x459/0x580 arch/x86/entry/common.c:194
 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:274
 do_syscall_64+0x126/0x140 arch/x86/entry/common.c:299
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413511
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffd2d339c10 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000413511
RDX: 0000001b31320000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: ffffffff8100821e R09: 0000000045cca788
R10: 00007ffd2d339cf0 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000760b28 R15: ffffffffffffffff

Allocated by task 769:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:487
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:501
 __do_kmalloc mm/slab.c:3655 [inline]
 __kmalloc+0x254/0x340 mm/slab.c:3664
 kmalloc include/linux/slab.h:557 [inline]
 sk_prot_alloc+0xb0/0x290 net/core/sock.c:1603
 sk_alloc+0x38/0x950 net/core/sock.c:1657
 nr_make_new net/netrom/af_netrom.c:476 [inline]
 nr_rx_frame+0xabc/0x1e40 net/netrom/af_netrom.c:959
 nr_loopback_timer+0x6a/0x140 net/netrom/nr_loopback.c:59
 call_timer_fn+0xec/0x200 kernel/time/timer.c:1322
 expire_timers kernel/time/timer.c:1366 [inline]
 __run_timers+0x7cd/0x9c0 kernel/time/timer.c:1685
 run_timer_softirq+0x4a/0x90 kernel/time/timer.c:1698
 __do_softirq+0x333/0x7c4 arch/x86/include/asm/paravirt.h:778

Freed by task 764:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x12a/0x1e0 mm/kasan/common.c:449
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:457
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x115/0x200 mm/slab.c:3756
 sk_prot_free net/core/sock.c:1640 [inline]
 __sk_destruct+0x567/0x660 net/core/sock.c:1726
 sk_destruct net/core/sock.c:1734 [inline]
 __sk_free+0x317/0x3e0 net/core/sock.c:1745
 sk_free net/core/sock.c:1756 [inline]
 sock_put include/net/sock.h:1725 [inline]
 sock_efree+0x60/0x80 net/core/sock.c:2042
 skb_release_head_state+0x100/0x220 net/core/skbuff.c:652
 skb_release_all net/core/skbuff.c:663 [inline]
 __kfree_skb+0x25/0x170 net/core/skbuff.c:679
 kfree_skb+0x6f/0xb0 net/core/skbuff.c:697
 nr_accept+0x4ef/0x650 net/netrom/af_netrom.c:819
 __sys_accept4+0x5bc/0x9a0 net/socket.c:1754
 __do_sys_accept net/socket.c:1795 [inline]
 __se_sys_accept net/socket.c:1792 [inline]
 __x64_sys_accept+0x7d/0x90 net/socket.c:1792
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880971b4480
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff8880971b4480, ffff8880971b4c80)
The buggy address belongs to the page:
page:ffffea00025c6d00 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0001dd8008 ffffea0001c22c88 ffff8880aa400e00
raw: 0000000000000000 ffff8880971b4480 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880971b4400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880971b4480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880971b4500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880971b4580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880971b4600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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