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BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc_not_zero+0x8f/0x2d0 lib/refcount.c:120
Read of size 4 at addr 0000000000000004 by task syz-executor0/8904

CPU: 0 PID: 8904 Comm: syz-executor0 Not tainted 4.17.0-rc1+ #10
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+0x1b9/0x294 lib/dump_stack.c:113
 kasan_report_error mm/kasan/report.c:352 [inline]
 kasan_report.cold.7+0x6d/0x2fe mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 refcount_inc_not_zero+0x8f/0x2d0 lib/refcount.c:120
 refcount_inc+0x15/0x70 lib/refcount.c:153
 llc_sap_hold include/net/llc.h:116 [inline]
 llc_ui_release+0xba/0x2b0 net/llc/af_llc.c:207
 sock_release+0x96/0x1b0 net/socket.c:594
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x34d/0x890 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1e4/0x290 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1aee/0x2730 kernel/exit.c:865
 do_group_exit+0x16f/0x430 kernel/exit.c:968
 get_signal+0x886/0x1960 kernel/signal.c:2469
 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455389
RSP: 002b:00007f4823508ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000072bf80 RCX: 0000000000455389
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072bf80
RBP: 000000000072bf80 R08: 0000000000000000 R09: 000000000072bf58
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffe321e30f R14: 00007f48235099c0 R15: 0000000000000001
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