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kernel BUG at fs/userfaultfd.c:883!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 1 PID: 15302 Comm: syz-executor1 Not tainted 4.18.0-rc7+ #77
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 35 c2 a0 ff <0f> 0b 4c 89 f7 e8 fb 9e de ff e9 11 fc ff ff 4c 89 e7 e8 4e 9e de 
RSP: 0018:ffff88019b4c7660 EFLAGS: 00010216
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc90005c89000
RDX: 0000000000000e9b RSI: ffffffff81db55fb RDI: 0000000000000000
RBP: ffff88019b4c77b0 R08: ffff8801c054e100 R09: 0000000000000000
R10: ffff8801c054e938 R11: b21129c27367def3 R12: ffff8801b82f3148
R13: 0000000000000000 R14: ffff8801b39f6318 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db100000(0063) knlGS:00000000f5f60b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007f0a5a700000 CR3: 00000001d8913000 CR4: 00000000001406e0
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_32_irqs_on arch/x86/entry/common.c:341 [inline]
 do_fast_syscall_32+0xcd5/0xfb2 arch/x86/entry/common.c:397
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f85cb9
Code: 55 08 8b 88 64 cd ff ff 8b 98 68 cd ff ff 89 c8 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 1c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 
RSP: 002b:00000000f5f600cc EFLAGS: 00000296 ORIG_RAX: 0000000000000078
RAX: fffffffffffffff4 RBX: 0000000000000000 RCX: 0000000020001f37
RDX: 0000000020001ffc RSI: 0000000020001000 RDI: 0000000020001000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 6a92cdaacc047291 ]---
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 35 c2 a0 ff <0f> 0b 4c 89 f7 e8 fb 9e de ff e9 11 fc ff ff 4c 89 e7 e8 4e 9e de 
RSP: 0018:ffff88019b4c7660 EFLAGS: 00010216
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc90005c89000
RDX: 0000000000000e9b RSI: ffffffff81db55fb RDI: 0000000000000000
RBP: ffff88019b4c77b0 R08: ffff8801c054e100 R09: 0000000000000000
R10: ffff8801c054e938 R11: b21129c27367def3 R12: ffff8801b82f3148
R13: 0000000000000000 R14: ffff8801b39f6318 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db100000(0063) knlGS:00000000f5f60b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007f0a5a700000 CR3: 00000001d8913000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400