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page fault in shm_delete_mapping

Status: fixed on 2019/10/02 01:44
Reported-by: syzbot+8f470a1bf36b47ae0040@syzkaller.appspotmail.com
Fix commit: db38f3713d52 in shmdt(), wait until shmat() completes before detaching.
First crash: 1808d, last: 1796d
▶ ▼ Duplicate bugs (1)
duplicates (1):
Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
panic: UBSan: Undefined Behavior in /syzkaller/managers/netbsd-kubsan/kernel/sys/kern/sysv_shm.c:LINE, member access wit syz 2 1663d 1663d 0/3 closed as dup on 2019/10/01 23:25

Sample crash report:
[  35.2211678] fatal page fault in supervisor mode
[  35.2322669] trap type 6 code 0 rip 0xffffffff80fe92cc cs 0x8 rflags 0x10287 cr2 0xffff900000000000 ilevel 0 rsp 0xffffa0016eef8c88
[  35.2433679] curlwp 0xffffa00012ef70c0 pid 846.2 lowest kstack 0xffffa0016eef12c0
[  35.2544650] panic: trap
[  35.2544650] cpu1: Begin traceback...
[  35.2544650] vpanic() at netbsd:vpanic+0x214
[  35.2655624] snprintf() at netbsd:snprintf
[  35.2766640] startlwp() at netbsd:startlwp
[  35.2877674] alltraps() at netbsd:alltraps+0xb2
[  35.2988634] shm_delete_mapping() at netbsd:shm_delete_mapping+0x7f
[  35.3099637] sys_shmat() at netbsd:sys_shmat+0x4cd
[  35.3210624] sys___syscall() at netbsd:sys___syscall+0xe2
[  35.3432612] syscall() at netbsd:syscall+0x348
[  35.3432612] --- syscall (number 198) ---
[  35.3543619] 7709d703f4aa:
[  35.3543619] cpu1: End traceback...

[  35.3543619] dumping to dev 4,1 (offset=0, size=0): not possible
[  35.3654585] rebooting...
SeaBIOS (version 1.8.2-20190308_060531-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 0x000f29d0: 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

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/05/08 00:43 netbsd 014f8a6c6f91 a7383bfa console log report syz ci2-netbsd
2019/05/20 12:03 netbsd aa2c9eca0f54 5a4461b0 console log report ci2-netbsd
2019/05/18 23:42 netbsd 04c7f3422885 5a4461b0 console log report ci2-netbsd
2019/05/18 04:55 netbsd d392fe408d81 40046286 console log report ci2-netbsd
2019/05/18 02:38 netbsd d392fe408d81 40046286 console log report ci2-netbsd
2019/05/15 22:50 netbsd 81fc8204d6e7 27b25dbc console log report ci2-netbsd
2019/05/15 14:59 netbsd 74e107a54608 bd4e3ac7 console log report ci2-netbsd
2019/05/15 07:51 netbsd 74e107a54608 bd4e3ac7 console log report ci2-netbsd
2019/05/15 06:49 netbsd 74e107a54608 bd4e3ac7 console log report ci2-netbsd
2019/05/12 22:04 netbsd 695cf0205ebb 5f302c04 console log report ci2-netbsd
2019/05/12 13:31 netbsd 308a4de880f8 c017728b console log report ci2-netbsd
2019/05/11 20:46 netbsd d2740109e7c1 0637a7f0 console log report ci2-netbsd
2019/05/11 15:24 netbsd 72d5b9e0840d 46caad94 console log report ci2-netbsd
2019/05/11 14:27 netbsd 72d5b9e0840d 46caad94 console log report ci2-netbsd
2019/05/11 13:30 netbsd 72d5b9e0840d 46caad94 console log report ci2-netbsd
2019/05/08 00:54 netbsd 014f8a6c6f91 a7383bfa console log report ci2-netbsd
2019/05/07 23:58 netbsd 014f8a6c6f91 a7383bfa console log report ci2-netbsd
* Struck through repros no longer work on HEAD.