[ 1987.4414886] ASan: Unauthorized Access In 0xffffffff80f7255c: Addr 0xffffb58012f2e6d8 [8 bytes, read, PoolUseAfterFree]
[ 1987.4540055] #0 0xffffffff80f7255c in knote <netbsd>
[ 1987.4665272] #1 0xffffffff8102f5eb in selnotify <netbsd>
[ 1987.4790421] #2 0xffffffff81027813 in pipeselwakeup <netbsd>
[ 1987.4790421] #3 0xffffffff81027af2 in pipeclose.part.0 <netbsd>
[ 1987.4915604] #4 0xffffffff81027d92 in pipe_close <netbsd>
[ 1987.5040753] #5 0xffffffff80f69af0 in closef <netbsd>
[ 1987.5040753] #6 0xffffffff80f6d7b5 in fd_free <netbsd>
[ 1987.5165922] #7 0xffffffff80f7accc in exit1 <netbsd>
[ 1987.5165922] #8 0xffffffff80fb8b94 in sigexit <netbsd>
[ 1987.5291102] #9 0xffffffff80fb92d7 in sendsig <netbsd>
[ 1987.5416269] #10 0xffffffff80f8c711 in lwp_userret <netbsd>
[ 1987.5541420] #11 0xffffffff8026b493 in syscall <netbsd>
[ 1987.5541420] ASan: Unauthorized Access In 0xffffffff80f7256c: Addr 0xffffb58012f2e738 [8 bytes, read, PoolUseAfterFree]
[ 1987.5792657] #0 0xffffffff80f7256c in knote <netbsd>
[ 1987.5792657] #1 0xffffffff8102f5eb in selnotify <netbsd>
[ 1987.5916915] #2 0xffffffff81027813 in pipeselwakeup <netbsd>
[ 1987.6042089] #3 0xffffffff81027af2 in pipeclose.part.0 <netbsd>
[ 1987.6167289] #4 0xffffffff81027d92 in pipe_close <netbsd>
[ 1987.6167289] #5 0xffffffff80f69af0 in closef <netbsd>
[ 1987.6301966] #6 0xffffffff80f6d7b5 in fd_free <netbsd>
[ 1987.6417597] #7 0xffffffff80f7accc in exit1 <netbsd>
[ 1987.6542774] #8 0xffffffff80fb8b94 in sigexit <netbsd>
[ 1987.6667941] #9 0xffffffff80fb92d7 in sendsig <netbsd>
[ 1987.6667941] #10 0xffffffff80f8c711 in lwp_userret <netbsd>
[ 1987.6793096] #11 0xffffffff8026b493 in syscall <netbsd>
[ 1987.6918276] panic: kernel diagnostic assertion "kn->kn_fop != NULL" failed: file "/syzkaller/managers/netbsd/kernel/sys/kern/kern_event.c", line 1653 
[ 1987.7043379] cpu1: Begin traceback...
[ 1987.7168553] vpanic() at netbsd:vpanic+0x214
[ 1987.7293760] _GLOBAL__sub_D_65535_0_cpu_configure() at netbsd:_GLOBAL__sub_D_65535_0_cpu_configure
[ 1987.7544106] knote() at netbsd:knote+0x117
[ 1987.7669276] selnotify() at netbsd:selnotify+0x30
[ 1987.7794427] pipeselwakeup() at netbsd:pipeselwakeup+0x47
[ 1987.8044790] pipeclose.part.0() at netbsd:pipeclose.part.0+0x8a
[ 1987.8295102] pipe_close() at netbsd:pipe_close+0x2b
[ 1987.8545443] closef() at netbsd:closef+0xf3
[ 1987.8670620] fd_free() at netbsd:fd_free+0x174
[ 1987.8795867] exit1() at netbsd:exit1+0x265
[ 1987.8920992] sigexit() at netbsd:sigexit+0x33c
[ 1987.9046115] sendsig() at netbsd:sendsig
[ 1987.9171290] lwp_userret() at netbsd:lwp_userret+0x2db
[ 1987.9296428] syscall() at netbsd:syscall+0x413
[ 1987.9421592] --- syscall (number 32) ---
[ 1987.9421592] 7dc40543e02a:
[ 1987.9546760] cpu1: End traceback...

[ 1987.9546760] dumping to dev 4,1 (offset=0, size=0): not possible
[ 1987.9671891] rebooting...
SeaBIOS (version 1.8.2-20190322_093631-google)
Total RAM Size = 0x00000001e0000000 = 7680 MiB
CPUs found: 2     Max CPUs supported: 2
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0 removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f29c0: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Booting from Hard Disk 0...

>> NetBSD/x86 BIOS Boot, Revision 5.10 (Tue Jul 17 14:59:51 UTC 2018) (from NetBSD 8.0)
>> Memory: 639/3144640 k

     1. Boot normally
     2. Boot single user
     3. Disable ACPI
     4. Disable ACPI and SMP
     5. Drop to boot prompt