KASAN: invalid memory access in amap_chunk_get

Status: closed as invalid on 2026/07/25 20:15
Reported-by: syzbot+395e2ca387211b07a4a6@syzkaller.appspotmail.com
First crash: 18d, last: 18d

Sample crash report:
panic: Caught invalid memory access at ffff800001b5eee8 size 4 op 0
Stopped at      db_enter+0x17:  popq    %rbp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*373176  53666      0         0x2          0    1  ndp
db_enter() at db_enter+0x17 sys/arch/amd64/amd64/db_interface.c:457
panic(ffffffff846334c7) at panic+0x270 sys/kern/subr_prf.c:198
__asan_load4_noabort(ffff800001b5eee8) at __asan_load4_noabort+0xa3
amap_chunk_get(ffff800001b5ee98,0,1,2) at amap_chunk_get+0x52 sys/uvm/uvm_amap.c:108
amap_add(ffff800001adb3e0,0,ffff800001864e30,0) at amap_add+0xda sys/uvm/uvm_amap.c:-1
uvm_fault_lower(ffff80003bb98c20,ffff80003bb98bc8,ffff80003bb98d20) at uvm_fault_lower+0x8e4 sys/uvm/uvm_fault.c:1468
uvm_fault(ffff800001afb5d8,f18b0ee1000,0,2) at uvm_fault+0x3ef sys/uvm/uvm_fault.c:657
upageflttrap(ffff80003bb98f10,f18b0ee152c) at upageflttrap+0xe0 sys/arch/amd64/amd64/trap.c:192
usertrap(ffff80003bb98f10) at usertrap+0x4f9 sys/arch/amd64/amd64/trap.c:640
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x76c97e06a630, count: 5
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: Caught invalid memory access at ffff800001b5eee8 size 4 op 0
ddb{1}> trace
db_enter() at db_enter+0x17 sys/arch/amd64/amd64/db_interface.c:457
panic(ffffffff846334c7) at panic+0x270 sys/kern/subr_prf.c:198
__asan_load4_noabort(ffff800001b5eee8) at __asan_load4_noabort+0xa3
amap_chunk_get(ffff800001b5ee98,0,1,2) at amap_chunk_get+0x52 sys/uvm/uvm_amap.c:108
amap_add(ffff800001adb3e0,0,ffff800001864e30,0) at amap_add+0xda sys/uvm/uvm_amap.c:-1
uvm_fault_lower(ffff80003bb98c20,ffff80003bb98bc8,ffff80003bb98d20) at uvm_fault_lower+0x8e4 sys/uvm/uvm_fault.c:1468
uvm_fault(ffff800001afb5d8,f18b0ee1000,0,2) at uvm_fault+0x3ef sys/uvm/uvm_fault.c:657
upageflttrap(ffff80003bb98f10,f18b0ee152c) at upageflttrap+0xe0 sys/arch/amd64/amd64/trap.c:192
usertrap(ffff80003bb98f10) at usertrap+0x4f9 sys/arch/amd64/amd64/trap.c:640
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x76c97e06a630, count: -10
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80003bb98870
rbx               0xffff80003bb988e0
rdx                                0
rcx               0xffff800028ff3ff0
rax                                0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0xffff80003bb98658
r11               0xffffffff814e1f30    x86_bus_space_io_read_1
r12               0xffffffff846334c7    db_machine_command_table+0x9b027
r13               0xffff800028ff4c08
r14               0xffff800028ff4e07
r15                              0x1
rip               0xffffffff81006567    db_enter+0x17
cs                               0x8
rflags                         0x246
rsp               0xffff80003bb98870
ss                                 0
db_enter+0x17:  popq    %rbp
ddb{1}> show proc
PROC (ndp) tid=373176 pid=53666 tcnt=1 stat=onproc
    flags process=2<EXEC> proc=0
    runpri=32, usrpri=76, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff800045ffc7e0,0xffff800045ffca88
    process=0xffff80003bb35830 user=0xffff80003bb8d000, vmspace=0xffff800001afb5d8
    estcpu=26, cpticks=16, pctcpu=0.4, user=0, sys=15, intr=0
ddb{1}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
  7446  359777   8202      0  2         0x2                sh
 98385  274902  10657      0  2    0x100002                ndp
 10657   39675  20372      0  3    0x10008a  sigsusp       sh
*53666  373176  35044      0  7         0x2                ndp
 35044  428173  89153      0  3    0x10008a  sigsusp       sh
 93689   33948  27666      0  2         0x2                arp
 24710  226380  13887      0  3    0x10008a  sigsusp       sh
 27666  181791  89135      0  3    0x10008a  sigsusp       sh
 17509  143617  83210      0  3    0x10008a  sigsusp       sh
 79799  514488  17917      0  2    0x100082                arp
 17917  505846  13189      0  3    0x10008a  sigsusp       sh
 89135  511778  82360      0  3        0x82  wait          syz-executor
 83210  516972  82360      0  3        0x82  wait          syz-executor
  7304   68447  82360      0  2       0xc82                syz-executor
  8202  144202  82360      0  3        0x82  wait          syz-executor
 89153  410669  82360      0  3        0x82  wait          syz-executor
 13189  193771  82360      0  3        0x82  wait          syz-executor
 13887   22091  82360      0  3        0x82  wait          syz-executor
 20372  216268  82360      0  3        0x82  wait          syz-executor
 82360  449337   7105      0  3        0x82  kqread        syz-executor
  7105   10638  28619      0  3    0x10008a  sigsusp       ksh
 28619   97769   9810      0  3        0x98  kqread        sshd-session
  9810  132531  73064      0  3        0x92  kqread        sshd-session
 78456  475334      1      0  3    0x100083  ttyin         getty
 73064  187345      1      0  3        0x88  kqread        sshd
 57126  429169  53408     74  3   0x1100092  bpf           pflogd
 53408  306199      1      0  3        0x80  sbwait        pflogd
 97084  447375  55243     73  2   0x1100090                syslogd
 55243  452335      1      0  3    0x100082  sbwait        syslogd
  6736   88481      1      0  3    0x100080  kqread        resolvd
 27929  168408  85703     77  3    0x100092  kqread        dhcpleased
 53888  289238  85703     77  3    0x100092  kqread        dhcpleased
 85703  257227      1      0  3        0x80  kqread        dhcpleased
 41923  322594      0      0  2     0x14200                smr
 95730  488388      0      0  2     0x14200                zerothread
 35324  257630      0      0  3     0x14200  aiodoned      aiodoned
 21069  203876      0      0  3     0x14200  syncer        update
 10493  124564      0      0  3     0x14200  cleaner       cleaner
 76846  188671      0      0  2     0x14200                reaper
 96734  207000      0      0  3     0x14200  pgdaemon      pagedaemon
 11779  317363      0      0  3     0x14200  bored         viomb
 80612  509698      0      0  3  0x40014200  acpi0         acpi0
 86858  437190      0      0  3  0x40014200                idle1
 75513  180671      0      0  3     0x14200  bored         softnet1
 43428  357660      0      0  3     0x14200  bored         softnet0
 60924  157124      0      0  3     0x14200  smrbar        systqmp
 48862  486312      0      0  3     0x14200  bored         systq
 24634  268378      0      0  3     0x14200  tmoslp        softclockmp
 78187  362087      0      0  3  0x40014200  tmoslp        softclock
  2477  388237      0      0  7  0x40014200                idle0
     1  347091      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{1}> show all locks
Process 53666 (ndp) thread 0xffff800045ffc548 (373176)
exclusive rwlock amaplk r = 0 (0xffff800001b14b28)
#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  uvm_fault_check+0xf69 sys/uvm/uvm_fault.c:834
#3  uvm_fault+0x1e7 sys/uvm/uvm_fault.c:627
#4  upageflttrap+0xe0 sys/arch/amd64/amd64/trap.c:192
#5  usertrap+0x4f9 sys/arch/amd64/amd64/trap.c:640
#6  recall_trap+0x8
shared rwlock vmmaplk r = 0 (0xffff800001afb6d8)
#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_read+0x55d sys/kern/kern_rwlock.c:413
#2  uvmfault_lookup+0x1a2 sys/uvm/uvm_fault.c:-1
#3  uvm_fault_check+0x43 sys/uvm/uvm_fault.c:693
#4  uvm_fault+0x1e7 sys/uvm/uvm_fault.c:627
#5  upageflttrap+0xe0 sys/arch/amd64/amd64/trap.c:192
#6  usertrap+0x4f9 sys/arch/amd64/amd64/trap.c:640
#7  recall_trap+0x8
Process 60924 (systqmp) thread 0xffff800045ffe000 (157124)
shared rwlock systqmp r = 0 (0xffffffff85403f18)
#0  witness_lock+0x632 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x632 sys/kern/subr_witness.c:1160
#1  taskq_thread+0x1ba sys/kern/kern_task.c:442
#2  proc_trampoline+0x10
ddb{1}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11050  12242K   12242K 166960K     12141        0
            pcb    17     24K      24K 166960K        17        0
         rtable   173      8K       9K 166960K       259        0
             pf    34     22K      22K 166960K        45        0
         ifaddr    35      8K       8K 166960K        37        0
        ifgroup    55      2K       2K 166960K        55        0
         sysctl     1      1K      13K 166960K         5        0
       counters    70     42K      42K 166960K        70        0
       ioctlops     0      0K       4K 166960K      1479        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1289     83K      83K 166960K      1358        0
      UFS quota     1     36K      36K 166960K         1        0
      UFS mount     5     44K      44K 166960K         5        0
            shm     2      2K       2K 166960K         2        0
         VM map     2      1K       1K 166960K         2        0
            sem     2      0K       0K 166960K         2        0
        dirhash    12      2K       2K 166960K        12        0
           ACPI  1734    201K     292K 166960K     11964        0
      file desc    21     77K      97K 166960K       116        0
           proc    69    128K     209K 166960K       523        0
        subproc    72      9K       9K 166960K        72        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     20K      20K 166960K         1        0
       in_multi    59      4K       4K 166960K        59        0
    ether_multi     1      0K       0K 166960K         1        0
            mrt     0      0K       0K 166960K         1        0
    ISOFS mount     1     36K      36K 166960K         1        0
  MSDOSFS mount     1     20K      20K 166960K         1        0
           ttys    25    182K     182K 166960K        25        0
           exec     0      0K       2K 166960K       367        0
   fusefs mount     1     36K      36K 166960K         1        0
            tdb     3      1K       1K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   217    248K     254K 166960K      3005        0
       UVM aobj     3      4K       4K 166960K         3        0
     pinsyscall    49     98K     110K 166960K      1237        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
            NDP    20      1K       1K 166960K        20        0
           temp    34   9162K    9172K 166960K      3745        0
         kqueue    13     40K      40K 166960K        25        0
      SYN cache     2     16K      16K 166960K         2        0
ddb{1}> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
plcache    128       28    0        0     1     0     1     1     0     8    0
rtpcb      120       27    0       22     1     0     1     1     0     8    0
rtentry    176       79    0        1     4     0     4     4     0     8    0
unpcb      144       39    0       22     1     0     1     1     0     8    0
syncache   336        4    0        4     2     1     1     1     0     8    1
tcpcb      736        8    0        4     1     0     1     1     0     8    0
arp        136       16    0        0     1     0     1     1     0     8    0
inpcb      328       61    0       54     2     0     2     2     0     8    1
nd6        152       10    0        0     1     0     1     1     0     8    0
kcovpl      48        8    0        0     1     0     1     1     0     8    0
pfosfp      40     1428    0     1005     5     0     5     5     0     8    0
pfosfpen   112     1428    0      714    21     0    21    21     0     8    0
pfstitem    24       14    0        0     1     0     1     1     0     8    0
pfstkey    128       14    0        0     1     0     1     1     0     8    0
pfstate    448       14    0        0     2     0     2     2     0     8    0
pfrule     1360      21    0       16     2     1     1     2     0     8    0
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256      289    0        0    19     0    19    19     0     8    0
art_table   40      290    0        0     3     0     3     3     0     8    0
art_node    32       79    0        5     1     0     1     1     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     1555    0       93    92     0    92    92     0     8    0
ffsino     296     1555    0       93   113     0   113   113     0     8    0
nchpl      144     1746    0       52    63     0    63    63     0     8    0
vnodes     216     1642    0        0    92     0    92    92     0     8    0
namei      1024    5270    0     5270     2     1     1     1     0     8    1
percpumem   16       51    0        0     1     0     1     1     0     8    0
kstatmem   264       27    0        0     2     0     2     2     0     8    0
scxspl     216     6436    0     6436     4     3     1     3     1     8    1
plimitpl   152       29    0       12     1     0     1     1     0     8    0
sigapl     424      433    0      379     7     0     7     7     0     8    0
knotepl    120       52    0        0     2     0     2     2     0     8    0
kqueuepl   224       21    0       12     1     0     1     1     0     8    0
pipepl     344      126    0       99     3     0     3     3     0     8    0
fdescpl    528      417    0      382     3     0     3     3     0     8    0
filepl     160     1524    0     1313     9     0     9     9     0     8    0
lockfpl    104        6    0        4     1     0     1     1     0     8    0
lockfspl    48        4    0        2     1     0     1     1     0     8    0
sessionpl  144       24    0       15     1     0     1     1     0     8    0
pgrppl      48       32    0       15     1     0     1     1     0     8    0
ucredpl    104       82    0       69     1     0     1     1     0     8    0
zombiepl   144      382    0      379     1     0     1     1     0     8    0
processpl  1232     433    0      379     5     0     5     5     0     8    0
procpl     664      435    0      379     5     0     5     5     0     8    0
sockpl     752      127    0       98     4     0     4     4     0     8    0
mcl8k      8192       3    0        0     1     0     1     1     0     8    0
mcl4k      4096     110    0        0    14     0    14    14     0     8    0
mcl2k      2048      31    0        0     4     0     4     4     0     8    0
mextrefs    64       31    0        0     1     0     1     1     0     8    0
mtagpl      96        3    0        0     1     0     1     1     0     8    0
mbufpl     256      178    0        0    12     0    12    12     0     8    0
bufpl      272     2276    0      105   145     0   145   145     0     8    0
anonpl      32     3904    0        0    32     0    32    32     0   222    0
amapchunkpl 152    8132    0     7782    15     0    15    15     0   158    0
amappl16   200     2050    0     2044     5     1     4     5     0     8    3
amappl15   192        4    0        3     1     0     1     1     0     8    0
amappl14   184      434    0      427     1     0     1     1     0     8    0
amappl13   176      122    0      108     1     0     1     1     0     8    0
amappl12   168      656    0      625     2     0     2     2     0     8    0
amappl11   160        8    0        8     1     1     0     1     0     8    0
amappl10   152       66    0       52     1     0     1     1     0     8    0
amappl9    144      273    0      273     1     1     0     1     0     8    0
amappl8    136       95    0       94     1     0     1     1     0     8    0
amappl7    128      141    0      124     1     0     1     1     0     8    0
amappl6    120      143    0      135     1     0     1     1     0     8    0
amappl5    112      132    0      122     1     0     1     1     0     8    0
amappl4    104      281    0      260     1     0     1     1     0     8    0
amappl3     96     1347    0     1258     4     1     3     3     0     8    0
amappl2     88      527    0      461     2     0     2     2     0     8    0
amappl1     80    10189    0     9482    17     1    16    16     0     8    0
amappl      88     2318    0     2189     4     0     4     4     0    92    0
uvmvnodes   80      100    0        0     3     0     3     3     0     8    0
dma4096    4096       1    0        1     1     1     0     1     0     8    0
dma1024    1024       1    0        0     1     0     1     1     0     8    0
dma256     256        6    0        6     1     1     0     1     0     8    0
dma128     128      253    0      253     1     1     0     1     0     8    0
dma64       64        6    0        6     1     1     0     1     0     8    0
dma32       32        7    0        7     1     1     0     1     0     8    0
dma16       16       18    0       17     1     0     1     1     0     8    0
aobjpl      72        2    0        0     1     0     1     1     0     8    0
uaddrrnd    24      417    0      382     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      417    0      382     1     0     1     1     0     8    0
vmmpekpl   168     5532    0     5500     2     0     2     2     0     8    0
vmmpepl    168    36602    0    34729    89     0    89    89     0   357    0
vmsppl     488      416    0      379     5     0     5     5     0     8    0
rwobjpl     80    14373    0    13230    26     1    25    25     0     8    0
pdppl      4096     843    0      758    99    10    89    89     0     8    4
pvpl        32     9313    0        0    77     1    76    76     0   265    0
pmappl     256      416    0      379     3     0     3     3     0     8    0
extentpl    40       46    0       28     1     0     1     1     0     8    0
phpool     112      405    0       15    12     0    12    12     0     8    0
ddb{1}> machine ddbcpu 0
Stopped at      x86_ipi_db+0x19:        leave
x86_ipi_db(ffffffff853a2ff0) at x86_ipi_db+0x19 sys/arch/amd64/amd64/db_interface.c:412
x86_ipi_handler() at x86_ipi_handler+0x112 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
acpicpu_idle() at acpicpu_idle+0x63c sys/dev/acpi/acpicpu_x86.c:-1
sched_idle(ffffffff853a2ff0) at sched_idle+0x566 sys/kern/kern_sched.c:204
end trace frame: 0x0, count: 10
ddb{0}> trace
x86_ipi_db(ffffffff853a2ff0) at x86_ipi_db+0x19 sys/arch/amd64/amd64/db_interface.c:412
x86_ipi_handler() at x86_ipi_handler+0x112 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
acpicpu_idle() at acpicpu_idle+0x63c sys/dev/acpi/acpicpu_x86.c:-1
sched_idle(ffffffff853a2ff0) at sched_idle+0x566 sys/kern/kern_sched.c:204
end trace frame: 0x0, count: -5
ddb{0}> machine ddbcpu 1
Stopped at      db_enter+0x17:  popq    %rbp
db_enter() at db_enter+0x17 sys/arch/amd64/amd64/db_interface.c:457
panic(ffffffff846334c7) at panic+0x270 sys/kern/subr_prf.c:198
__asan_load4_noabort(ffff800001b5eee8) at __asan_load4_noabort+0xa3
amap_chunk_get(ffff800001b5ee98,0,1,2) at amap_chunk_get+0x52 sys/uvm/uvm_amap.c:108
amap_add(ffff800001adb3e0,0,ffff800001864e30,0) at amap_add+0xda sys/uvm/uvm_amap.c:-1
uvm_fault_lower(ffff80003bb98c20,ffff80003bb98bc8,ffff80003bb98d20) at uvm_fault_lower+0x8e4 sys/uvm/uvm_fault.c:1468
uvm_fault(ffff800001afb5d8,f18b0ee1000,0,2) at uvm_fault+0x3ef sys/uvm/uvm_fault.c:657
upageflttrap(ffff80003bb98f10,f18b0ee152c) at upageflttrap+0xe0 sys/arch/amd64/amd64/trap.c:192
usertrap(ffff80003bb98f10) at usertrap+0x4f9 sys/arch/amd64/amd64/trap.c:640
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x76c97e06a630, count: 5
ddb{1}> trace
db_enter() at db_enter+0x17 sys/arch/amd64/amd64/db_interface.c:457
panic(ffffffff846334c7) at panic+0x270 sys/kern/subr_prf.c:198
__asan_load4_noabort(ffff800001b5eee8) at __asan_load4_noabort+0xa3
amap_chunk_get(ffff800001b5ee98,0,1,2) at amap_chunk_get+0x52 sys/uvm/uvm_amap.c:108
amap_add(ffff800001adb3e0,0,ffff800001864e30,0) at amap_add+0xda sys/uvm/uvm_amap.c:-1
uvm_fault_lower(ffff80003bb98c20,ffff80003bb98bc8,ffff80003bb98d20) at uvm_fault_lower+0x8e4 sys/uvm/uvm_fault.c:1468
uvm_fault(ffff800001afb5d8,f18b0ee1000,0,2) at uvm_fault+0x3ef sys/uvm/uvm_fault.c:657
upageflttrap(ffff80003bb98f10,f18b0ee152c) at upageflttrap+0xe0 sys/arch/amd64/amd64/trap.c:192
usertrap(ffff80003bb98f10) at usertrap+0x4f9 sys/arch/amd64/amd64/trap.c:640
recall_trap() at recall_trap+0x8
end of kernel
end trace frame: 0x76c97e06a630, count: -10

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/11 14:06 https://github.com/blackgnezdo/openbsd-src.git syzbot-kasan 275dedaf93b0 d78ea535 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-kasan KASAN: invalid memory access in amap_chunk_get
* Struck through repros no longer work on HEAD.