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kernel BUG at fs/userfaultfd.c:883!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 0 PID: 9750 Comm: syz-executor4 Not tainted 4.18.0-rc5+ #153
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:userfaultfd_release+0x5fb/0x770 fs/userfaultfd.c:882
Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 a1 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 be a0 ff <0f> 0b 4c 89 f7 e8 0b 9e de ff e9 11 fc ff ff 4c 89 e7 e8 5e 9d de 
RSP: 0018:ffff88019932f6b0 EFLAGS: 00010212
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc90009a5a000
RDX: 0000000000000f81 RSI: ffffffff81db4d0b RDI: 0000000000000000
RBP: ffff88019932f800 R08: ffff8801cf348480 R09: 0000000000000000
R10: ffff8801cf348cb8 R11: 2173d2ec91a24ef6 R12: ffff8801b7be5738
R13: 0000000000000000 R14: ffff8801b9327d68 R15: 0000000000000000
FS:  00007fb2c298e700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd11119fd8 CR3: 00000001d7d5e000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __fput+0x355/0x8b0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 get_signal+0x1559/0x1970 kernel/signal.c:2298
 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x2e0/0x370 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455ab9
Code: 1d ba 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007fb2c298dc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: fffffffffffffff4 RBX: 00007fb2c298e6d4 RCX: 0000000000455ab9
RDX: 0000000020001ffc RSI: 0000000020001f37 RDI: 0000000000000000
RBP: 000000000072bff0 R08: 0000000020001000 R09: 0000000000000000
R10: 0000000020001000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004bb85d R14: 00000000004c8d28 R15: 0000000000000002
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 1da854e9b2d80d53 ]---
RIP: 0010:userfaultfd_release+0x5fb/0x770 fs/userfaultfd.c:882
Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 a1 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 be a0 ff <0f> 0b 4c 89 f7 e8 0b 9e de ff e9 11 fc ff ff 4c 89 e7 e8 5e 9d de 
RSP: 0018:ffff88019932f6b0 EFLAGS: 00010212
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc90009a5a000
RDX: 0000000000000f81 RSI: ffffffff81db4d0b RDI: 0000000000000000
RBP: ffff88019932f800 R08: ffff8801cf348480 R09: 0000000000000000
R10: ffff8801cf348cb8 R11: 2173d2ec91a24ef6 R12: ffff8801b7be5738
R13: 0000000000000000 R14: ffff8801b9327d68 R15: 0000000000000000
FS:  00007fb2c298e700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd11119fd8 CR3: 00000001d7d5e000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400