KASAN: invalid memory access in rw_status

Status: upstream: reported on 2026/07/14 07:48
Reported-by: syzbot+63aa5c5f0765df8a5ed5@syzkaller.appspotmail.com
First crash: 17d, last: 12d

Sample crash report:
panic: Caught invalid memory access at ffff800045ff7d38 size 8 op 0
Stopped at      db_enter+0x17:  popq    %rbp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
 467644  83592      0           0          0    0  syz-executor
*102877  20848      0           0  0x4000000    1  syz-executor
db_enter() at db_enter+0x17 sys/arch/amd64/amd64/db_interface.c:457
panic(ffffffff84631de8) at panic+0x270 sys/kern/subr_prf.c:198
__asan_load8_noabort(ffff800045ff7d38) at __asan_load8_noabort+0xde kasan_shadow_check sys/kern/subr_kasan.c:-1 [inline]
__asan_load8_noabort(ffff800045ff7d38) at __asan_load8_noabort+0xde sys/kern/subr_kasan.c:1099
rw_status(ffff800045ff7d38) at rw_status+0x27 atomic_load_long sys/sys/atomic.h:213 [inline]
rw_status(ffff800045ff7d38) at rw_status+0x27 sys/kern/kern_rwlock.c:517
KQRELE(ffff8000017d09a0) at KQRELE+0x77 sys/kern/kern_event.c:244
kqueue_close(ffff8000017dc788,ffff800045ffcfa8) at kqueue_close+0x70 sys/kern/kern_event.c:1956
fdrop(ffff8000017dc788,ffff800045ffcfa8) at fdrop+0x1c3 sys/kern/kern_descrip.c:1281
fd_iterfile(ffff8000017dc788,ffff800045ffcfa8) at fd_iterfile+0x162 sys/kern/kern_descrip.c:222
sysctl_file(ffff8000299a3de8,4,200000000040,ffff8000299a3dc0,ffff800045ffcfa8) at sysctl_file+0x312f sys/kern/kern_sysctl.c:-1
kern_sysctl_dirs(49,ffff8000299a3de8,4,200000000040,ffff8000299a3dc0,200000000440,4,1ffff00005334734) at kern_sysctl_dirs+0x265 sys/kern/kern_sysctl.c:415
kern_sysctl(ffff8000299a3de4,5,200000000040,ffff8000299a3dc0,200000000440,fe6,ffff8000299a4030) at kern_sysctl+0x1ce sys/kern/kern_sysctl.c:529
sys_sysctl(ffff800045ffcfa8,ffff8000299a4030,ffff8000299a3fa0) at sys_sysctl+0x54f sys/kern/kern_sysctl.c:309
syscall(ffff8000299a4030) at syscall+0x1089 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff8000299a4030) at syscall+0x1089 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9db248627b0, count: 1
https://www.openbsd.org/ddb.html describes the minimum info required in bug
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ddb{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
*cpu1: Caught invalid memory access at ffff800045ff7d38 size 8 op 0
ddb{1}> show kasan
KASAN: invalid read of 8 bytes at 0xffff800045ff7d38 from pc 0xffffffff817932a7
KASAN: first bad byte at 0xffff800045ff7d38 (+0); shadow 0xfd: pool use-after-free (or unallocated item)
KASAN: 0xffff800045ff7d38 is 72 bytes inside the 528-byte item [0xffff800045ff7cf0..0xffff800045ff7f00) in pool 'fdescpl'
KASAN: allocated at:
#0  pool_get+0x770 sys/kern/subr_pool.c:733
#1  fdcopy+0x55 fdinit sys/kern/kern_descrip.c:1070 [inline]
#1  fdcopy+0x55 sys/kern/kern_descrip.c:1109
#2  process_new+0x601 sys/kern/kern_fork.c:277
#3  fork1+0x533 sys/kern/kern_fork.c:408
#4  syscall+0x1089 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#4  syscall+0x1089 sys/arch/amd64/amd64/trap.c:783
#5  Xsyscall+0x128
KASAN: freed at:
#0  pool_put+0x79 sys/kern/subr_pool.c:918
#1  exit1+0x81e sys/kern/kern_exit.c:215
#2  sys_exit+0x4a
#3  syscall+0x1089 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#3  syscall+0x1089 sys/arch/amd64/amd64/trap.c:783
#4  Xsyscall+0x128
KASAN: pc: rw_status+0x27
KASAN: call trace:
#0  __asan_load8_noabort+0xbd kasan_shadow_check sys/kern/subr_kasan.c:-1 [inline]
#0  __asan_load8_noabort+0xbd sys/kern/subr_kasan.c:1099
#1  rw_status+0x27 atomic_load_long sys/sys/atomic.h:213 [inline]
#1  rw_status+0x27 sys/kern/kern_rwlock.c:517
#2  KQRELE+0x77 sys/kern/kern_event.c:244
#3  kqueue_close+0x70 sys/kern/kern_event.c:1956
#4  fdrop+0x1c3 sys/kern/kern_descrip.c:1281
#5  fd_iterfile+0x162 sys/kern/kern_descrip.c:222
#6  sysctl_file+0x312f sys/kern/kern_sysctl.c:-1
#7  kern_sysctl_dirs+0x265 sys/kern/kern_sysctl.c:415
#8  kern_sysctl+0x1ce sys/kern/kern_sysctl.c:529
#9  sys_sysctl+0x54f sys/kern/kern_sysctl.c:309
#10 syscall+0x1089 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#10 syscall+0x1089 sys/arch/amd64/amd64/trap.c:783
#11 Xsyscall+0x128
KASAN: shadow of 0xffff800045ff7c00..0xffff800045ff7e80 (1 cell = 8 bytes):
 0xffff800045ff7c00: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
 0xffff800045ff7c80: fd fd fd fd fd fd fd fd fd fd fd fd fd fd 08 08
>0xffff800045ff7d00: fd fd fd fd fd fd fd[fd]fd fd fd fd fd fd fd fd
 0xffff800045ff7d80: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
 0xffff800045ff7e00: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
KASAN: legend: 00 valid; 01..07 partial; fb malloc redzone; fc malloc freed; fd pool freed; fe kmem; fa global; f1..f4/f8 stack/scope
ddb{1}> trace
db_enter() at db_enter+0x17 sys/arch/amd64/amd64/db_interface.c:457
panic(ffffffff84631de8) at panic+0x270 sys/kern/subr_prf.c:198
__asan_load8_noabort(ffff800045ff7d38) at __asan_load8_noabort+0xde kasan_shadow_check sys/kern/subr_kasan.c:-1 [inline]
__asan_load8_noabort(ffff800045ff7d38) at __asan_load8_noabort+0xde sys/kern/subr_kasan.c:1099
rw_status(ffff800045ff7d38) at rw_status+0x27 atomic_load_long sys/sys/atomic.h:213 [inline]
rw_status(ffff800045ff7d38) at rw_status+0x27 sys/kern/kern_rwlock.c:517
KQRELE(ffff8000017d09a0) at KQRELE+0x77 sys/kern/kern_event.c:244
kqueue_close(ffff8000017dc788,ffff800045ffcfa8) at kqueue_close+0x70 sys/kern/kern_event.c:1956
fdrop(ffff8000017dc788,ffff800045ffcfa8) at fdrop+0x1c3 sys/kern/kern_descrip.c:1281
fd_iterfile(ffff8000017dc788,ffff800045ffcfa8) at fd_iterfile+0x162 sys/kern/kern_descrip.c:222
sysctl_file(ffff8000299a3de8,4,200000000040,ffff8000299a3dc0,ffff800045ffcfa8) at sysctl_file+0x312f sys/kern/kern_sysctl.c:-1
kern_sysctl_dirs(49,ffff8000299a3de8,4,200000000040,ffff8000299a3dc0,200000000440,4,1ffff00005334734) at kern_sysctl_dirs+0x265 sys/kern/kern_sysctl.c:415
kern_sysctl(ffff8000299a3de4,5,200000000040,ffff8000299a3dc0,200000000440,fe6,ffff8000299a4030) at kern_sysctl+0x1ce sys/kern/kern_sysctl.c:529
sys_sysctl(ffff800045ffcfa8,ffff8000299a4030,ffff8000299a3fa0) at sys_sysctl+0x54f sys/kern/kern_sysctl.c:309
syscall(ffff8000299a4030) at syscall+0x1089 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff8000299a4030) at syscall+0x1089 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9db248627b0, count: -14
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff8000299a3230
rbx               0xffff8000299a32a0
rdx                                0
rcx               0xffff800028ff3ff0
rax                                0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0xffff8000299a3018
r11               0xffffffff82744c00    x86_bus_space_io_read_1
r12               0xffffffff84631de8    ucc_ca+0x9ab48
r13               0xffff800028ff4c08
r14               0xffff800028ff4e07
r15                              0x1
rip               0xffffffff81a97a67    db_enter+0x17
cs                               0x8
rflags                         0x246
rsp               0xffff8000299a3230
ss                              0x10
db_enter+0x17:  popq    %rbp
ddb{1}> show proc
PROC (syz-executor) tid=102877 pid=20848 tcnt=4 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=86, usrpri=83, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff800045ffc7e0,0xffff8000298a5ca0
    process=0xffff800045ff39e0 user=0xffff800029999000, vmspace=0xffff800001c3d5d0
    estcpu=33, cpticks=33, pctcpu=0.18, user=0, sys=33, intr=0
ddb{1}> ps
   PID     TID   PPID   UID  S      PRLAGS     PFLAGS WAIT      COMMAND
 83592  467644  68699     0  7           0          0           syz-executor
 83592   85825  68699     0  2           0  0x4000080           syz-executor
 33582  488622  40196     0  2           0          0           syz-executor
 34437  114620      1     0  3         0x2       0x80 nanoslp   getty
 95221  103903   9164     0  2        0x10      0xc80           syz-executor
 95221   76993   9164     0  3        0x10  0x4000080 kqpoll    syz-executor
 95221  487586   9164     0  3        0x10  0x4000080 fsleep    syz-executor
 20848  390180  22985     0  2           0      0xc80           syz-executor
*20848  102877  22985     0  7           0  0x4000000           syz-executor
 20848  183279  22985     0  3           0  0x4000080 fsleep    syz-executor
 20848  523695  22985     0  3           0  0x4000080 fsleep    syz-executor
 56848  141082  99543     0  2           0      0xc80           syz-executor
 56848  417742  99543     0  3           0  0x4000080 bell      syz-executor
 56848   43145  99543     0  3           0  0x4000080 fsleep    syz-executor
 56848  264860  99543     0  3           0  0x4000080 fsleep    syz-executor
  5877  110070  62933     0  3      0x1010     0x2000 suspend   syz-executor
  5877  329629  62933     0  2      0x1010  0x4080080           syz-executor
  5877  292232  62933     0  2      0x1010  0x4080080           syz-executor
 76593  330471      0     0  3     0x14000      0x280 nfsidl    nfsio
 81947  262045      0     0  3     0x14000      0x280 nfsidl    nfsio
 96651  149875      0     0  3     0x14000      0x280 nfsidl    nfsio
  3268   54910      0     0  3     0x14000      0x280 nfsidl    nfsio
 73745  468409      0     0  3     0x14000      0x280 nfsidl    nfsio
 62487  217326      0     0  3     0x14000      0x280 nfsidl    nfsio
 95250  479135      0     0  3     0x14000      0x280 nfsidl    nfsio
 24987  163280      0     0  3     0x14000      0x280 nfsidl    nfsio
 21203  481615      0     0  3     0x14000      0x280 nfsidl    nfsio
 29101  325231      0     0  3     0x14000      0x280 nfsidl    nfsio
  6555  119514      0     0  3     0x14000      0x280 nfsidl    nfsio
 80866  365130      0     0  3     0x14000      0x280 nfsidl    nfsio
 91652   16122      0     0  3     0x14000      0x280 nfsidl    nfsio
 68666  347760      0     0  3     0x14000      0x280 nfsidl    nfsio
 95331  284160      0     0  3     0x14000      0x280 nfsidl    nfsio
 44277  230385      0     0  3     0x14000      0x280 nfsidl    nfsio
 46414  498044      0     0  3     0x14000      0x280 nfsidl    nfsio
 34619  205723      0     0  3     0x14000      0x280 nfsidl    nfsio
 34388  223826      0     0  3     0x14000      0x280 nfsidl    nfsio
 96863  357386      0     0  3     0x14000      0x280 nfsidl    nfsio
 59115  410936  10887     0  2         0x2          0           syz-executor
 40196  185588  10887     0  2         0x2      0xc80           syz-executor
 99543  160992  10887     0  2         0x2      0xc80           syz-executor
 39123  218020  10887     0  3         0x2          0 getblk    syz-executor
 22985  309123  10887     0  2         0x2      0xc80           syz-executor
 68699  252342  10887     0  2         0x2          0           syz-executor
 62933  367436  10887     0  2         0x2      0xc80           syz-executor
  9164  263627  10887     0  2         0x2      0xc80           syz-executor
 10887  373536      1     0  3         0x2       0x80 kqread    syz-executor
 56601  121328      0     0  3     0x14000      0x200 bored     smr
 40902  139904      0     0  2     0x14000      0x200           zerothread
 71477  490934      0     0  3     0x14000      0x200 aiodoned  aiodoned
 50098  281661      0     0  3     0x14000      0x200 syncer    update
 39115  398519      0     0  3     0x14000      0x200 cleaner   cleaner
 37097  478541      0     0  3     0x14000      0x200 reaper    reaper
 47026  370450      0     0  3     0x14000      0x200 pgdaemon  pagedaemon
 85393   65920      0     0  3     0x14000      0x200 bored     viomb
 95489  313845      0     0  3     0x14000 0x40000200 acpi0     acpi0
 28863  354295      0     0  3     0x14000 0x40000200           idle1
 99232  411708      0     0  3     0x14000      0x200 bored     softnet1
 19129  134719      0     0  2     0x14000      0x200           softnet0
 71683  261127      0     0  3     0x14000      0x200 bored     systqmp
 97995  181488      0     0  3     0x14000      0x200 bored     systq
 26991  283882      0     0  3     0x14000      0x200 tmoslp    softclockmp
  3704  514113      0     0  3     0x14000 0x40000200 tmoslp    softclock
 60492  346101      0     0  3     0x14000 0x40000200           idle0
     1  394377      0     0  3         0x2       0x80 wait      init
     0       0     -1     0  3     0x10000      0x200 scheduler swapper
ddb{1}> show all locks
Process 59115 (syz-executor) thread 0xffff800045ffc548 (410936)
exclusive rrwlock inode r = 0 (0xffff800001a276c8)
#0  witness_lock+0x632 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x632 sys/kern/subr_witness.c:1160
#1  rw_do_enter_write+0x53e sys/kern/kern_rwlock.c:320
#2  rrw_enter+0xf0 sys/kern/kern_rwlock.c:621
#3  VOP_LOCK+0x17e sys/kern/vfs_vops.c:527
#4  vn_lock+0xca sys/kern/vfs_vnops.c:576
#5  vget+0x321 sys/kern/vfs_subr.c:694
#6  ufs_ihashget+0x233 sys/ufs/ufs/ufs_ihash.c:98
#7  

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/20 00:45 https://github.com/blackgnezdo/openbsd-src.git syzbot-kasan 7db9963a4e65 72524a66 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-kasan KASAN: invalid memory access in rw_status
2026/07/14 07:47 https://github.com/blackgnezdo/openbsd-src.git syzbot-kasan 85db861bb080 2130f682 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-kasan KASAN: invalid memory access in rw_status
* Struck through repros no longer work on HEAD.