syzbot


assert "refs > NUM" failed in kern_synch.c

Status: upstream: reported on 2025/09/09 19:41
Reported-by: syzbot+e0d831b30701aaff71bd@syzkaller.appspotmail.com
First crash: 270d, last: 40d

Sample crash report:
login: panic: kernel diagnostic assertion "refs > 1" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 920
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  15385   3711      0           0          0    0  syz-executor
*100605  49175      0           0  0x4000000    1  syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834522ec) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff83490b1b,ffffffff8349eb95,398,ffffffff8345ae1a) at __assert+0x29 sys/kern/subr_prf.c:-1
refcnt_take(ffff8000015fe008) at refcnt_take+0x109 sys/kern/kern_synch.c:921
if_getgroupmembers(ffff80002a285da0) at if_getgroupmembers+0x11d sys/net/if.c:3256
sys_ioctl(ffff8000357b4d20,ffff80002a285f80,ffff80002a285ed0) at sys_ioctl+0x674 sys/kern/sys_generic.c:-1
syscall(ffff80002a285f80) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a285f80) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x2fccab52530, count: 7
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.
ddb{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
*cpu1: kernel diagnostic assertion "refs > 1" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 920
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834522ec) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff83490b1b,ffffffff8349eb95,398,ffffffff8345ae1a) at __assert+0x29 sys/kern/subr_prf.c:-1
refcnt_take(ffff8000015fe008) at refcnt_take+0x109 sys/kern/kern_synch.c:921
if_getgroupmembers(ffff80002a285da0) at if_getgroupmembers+0x11d sys/net/if.c:3256
sys_ioctl(ffff8000357b4d20,ffff80002a285f80,ffff80002a285ed0) at sys_ioctl+0x674 sys/kern/sys_generic.c:-1
syscall(ffff80002a285f80) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a285f80) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x2fccab52530, count: -8
ddb{1}> 

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/27 15:39 openbsd 80ba1745ccfd 0f700595 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore assert "refs > NUM" failed in kern_synch.c
2026/04/06 19:02 openbsd 8a4a3a78bbe7 4b3d9a38 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-setuid assert "refs > NUM" failed in kern_synch.c
2026/02/09 07:36 openbsd e6ae0557afc8 018ebef2 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main assert "refs > NUM" failed in kern_synch.c
2026/01/26 07:23 openbsd 401b985036af 55756628 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore assert "refs > NUM" failed in kern_synch.c
2025/11/30 12:16 openbsd 0086034dedf2 01c07bfe .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore assert "refs > NUM" failed in kern_synch.c
2025/10/23 11:36 openbsd 22e0e8faf4c6 c0460fcd .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main assert "refs > NUM" failed in kern_synch.c
2025/09/09 19:40 openbsd 3efab2192dd6 fdeaa69b .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore assert "refs > NUM" failed in kern_synch.c
* Struck through repros no longer work on HEAD.