syzbot


uvm_fault: checkalias (2)

Status: upstream: reported on 2026/01/25 01:20
Reported-by: syzbot+8cc1e70cfa72da226f48@syzkaller.appspotmail.com
First crash: 15d, last: 15d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd uvm_fault: checkalias -1 8 545d 671d 0/3 auto-obsoleted due to no activity on 2024/11/11 03:51

Sample crash report:
uvm_fault(0xfffffd806c9a8d00, 0x18, 0, 1) -> e
kernel: page fault trap, code=0
Stopped at      checkalias+0xb7:        movl    0x18(%r13),%ebx
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*483045  67526      0           0  0x4000000    0  syz-executor
checkalias(fffffd806b3350f0,21700,0) at checkalias+0xb7 sys/kern/vfs_subr.c:574
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 getdevvp sys/kern/vfs_subr.c:-1 [inline]
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 sys/kern/vfs_subr.c:517
spec_open_clone(ffff80003c13f0b8) at spec_open_clone+0x1e2 sys/kern/spec_vnops.c:713
spec_open(ffff80003c13f0b8) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd806f4b8030,9,fffffd8007bfd750,ffff80002a7762a0) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c13f300,9,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a7762a0,ffffff9c,200000000080,8,0,ffff80003c13f4a0) at doopenat+0x34d sys/kern/vfs_syscalls.c:1138
syscall(ffff80003c13f550) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c13f550) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x689c533c320, count: 6
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> 
ddb> set $lines = 0
ddb> set $maxwidth = 0
ddb> show panic
*cpu0: uvm_fault(0xfffffd806c9a8d00, 0x18, 0, 1) -> e
ddb> trace
checkalias(fffffd806b3350f0,21700,0) at checkalias+0xb7 sys/kern/vfs_subr.c:574
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 getdevvp sys/kern/vfs_subr.c:-1 [inline]
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 sys/kern/vfs_subr.c:517
spec_open_clone(ffff80003c13f0b8) at spec_open_clone+0x1e2 sys/kern/spec_vnops.c:713
spec_open(ffff80003c13f0b8) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd806f4b8030,9,fffffd8007bfd750,ffff80002a7762a0) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c13f300,9,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a7762a0,ffffff9c,200000000080,8,0,ffff80003c13f4a0) at doopenat+0x34d sys/kern/vfs_syscalls.c:1138
syscall(ffff80003c13f550) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c13f550) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x689c533c320, count: -9
ddb> show registers
rdi                         0x131700    acpi_pdirpa+0x11d571
rsi                          0x21700    acpi_pdirpa+0xd571
rbp               0xffff80003c13ef60
rbx                         0x131700    acpi_pdirpa+0x11d571
rdx                                0
rcx               0xfffffd806b335a88
rax               0xffff80002a7762a0
r8                                 0
r9                0xffffffffffffffff
r10               0x770cd8ef8e37f133
r11               0x9f2d59022466b861
r12                                0
r13                                0
r14                          0x21700    acpi_pdirpa+0xd571
r15               0xfffffd806b952e98
rip               0xffffffff81d90357    checkalias+0xb7
cs                               0x8
rflags                       0x10246    __ALIGN_SIZE+0xf246
rsp               0xffff80003c13eef0
ss                                 0
checkalias+0xb7:        movl    0x18(%r13),%ebx
ddb> show proc
PROC (syz-executor) tid=483045 pid=67526 tcnt=4 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=82, usrpri=82, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff800033cf8800,0xffff80003c96b790
    process=0xffff8000ffff8018 user=0xffff80003c13a000, vmspace=0xfffffd806c9a8d00
    estcpu=32, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0
ddb> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 92654  257047  35311      0  2           0                syz-executor
 92654  361974  35311      0  2   0x4000000                syz-executor
 88542  171981  10131      0  2           0                syz-executor
 88542   44055  10131      0  2   0x4000000                syz-executor
 60975  430805  15409      0  2           0                syz-executor
 60975  412014  15409      0  2   0x4000000                syz-executor
 60975  288502  15409      0  2   0x4000000                syz-executor
 38602  514815  92394      0  2           0                syz-executor
 38602   59500  92394      0  3   0x4000080  fsleep        syz-executor
 91458   80886  94095      0  2           0                syz-executor
 91458  186700  94095      0  3   0x4000080  dtread        syz-executor
 91458  102237  94095      0  2   0x4000000                syz-executor
 67526  329265  43860      0  2           0                syz-executor
*67526  483045  43860      0  7   0x4000000                syz-executor
 67526  244225  43860      0  3   0x4000080  fsleep        syz-executor
 67526  120181  43860      0  3   0x4000080  fsleep        syz-executor
 97265   47808      0      0  3     0x14200  acct          acct
 94095  488820  20829      0  3        0x82  nanoslp       syz-executor
 43860  458576  20829      0  3        0x82  nanoslp       syz-executor
 39505  210500      0      0  3     0x14280  nfsidl        nfsio
 30757  479625      0      0  3     0x14280  nfsidl        nfsio
 64767  353777      0      0  3     0x14280  nfsidl        nfsio
 16914  281616      0      0  3     0x14280  nfsidl        nfsio
 25223  247479      0      0  3     0x14280  nfsidl        nfsio
 35882   68383      0      0  3     0x14280  nfsidl        nfsio
 11731  131687      0      0  3     0x14280  nfsidl        nfsio
 10508  335128      0      0  3     0x14280  nfsidl        nfsio
 19618  116501      0      0  3     0x14280  nfsidl        nfsio
 77629   39878      0      0  3     0x14280  nfsidl        nfsio
 83831  521565      0      0  3     0x14280  nfsidl        nfsio
 31908  513087      0      0  3     0x14280  nfsidl        nfsio
 39536  465560      0      0  3     0x14280  nfsidl        nfsio
 90477  371430      0      0  3     0x14280  nfsidl        nfsio
 86129  487776      0      0  3     0x14280  nfsidl        nfsio
 55008   27307      0      0  3     0x14280  nfsidl        nfsio
 40971   63226      0      0  3     0x14280  nfsidl        nfsio
 97840  311445      0      0  3     0x14280  nfsidl        nfsio
 50743  440420      0      0  3     0x14280  nfsidl        nfsio
  7273  463267      0      0  3     0x14280  nfsidl        nfsio
 35311   51555  20829      0  3        0x82  nanoslp       syz-executor
 15409  300995  20829      0  3        0x82  nanoslp       syz-executor
 12312  373542  20829      0  2         0x2                syz-executor
 92394  217313  20829      0  3        0x82  nanoslp       syz-executor
 10131  238433  20829      0  3        0x82  nanoslp       syz-executor
 66650  208374  20829      0  2         0x2                syz-executor
 20829   26986   6716      0  3        0x82  kqread        syz-executor
  6716  288351  31939      0  3    0x10008a  sigsusp       ksh
 31939   36332  47309      0  3        0x98  kqread        sshd-session
 47309   73072  80245      0  3        0x92  kqread        sshd-session
 92863  174675      1      0  3    0x100083  ttyopn        getty
 80245  335252      1      0  3        0x88  kqread        sshd
 12575   11532  87942     73  3   0x1100090  kqread        syslogd
 87942  407723      1      0  3    0x100082  sbwait        syslogd
 74653   87820      1      0  3    0x100080  kqread        resolvd
 76876  125205  48388     77  3    0x100092  kqread        dhcpleased
 94643  176573  48388     77  3    0x100092  kqread        dhcpleased
 48388   75616      1      0  3        0x80  kqread        dhcpleased
 72438   60371      0      0  3     0x14200  bored         smr
 32062  214438      0      0  2     0x14200                zerothread
 46916  287279      0      0  3     0x14200  aiodoned      aiodoned
 61752  247499      0      0  3     0x14200  syncer        update
 67181    8451      0      0  3     0x14200  cleaner       cleaner
 30286  519371      0      0  3     0x14200  reaper        reaper
 18621  379845      0      0  3     0x14200  pgdaemon      pagedaemon
 68486  288661      0      0  3     0x14200  bored         viomb
 66867  395892      0      0  3  0x40014200  acpi0         acpi0
 85458  382611      0      0  2     0x14200                softnet0
  3236  353594      0      0  3     0x14200  bored         systqmp
 42610   51851      0      0  3     0x14200  bored         systq
 68514  332362      0      0  3  0x40014200  tmoslp        softclock
 90940  236375      0      0  3  0x40014200                idle0
     1  260551      0      0  3        0x82  wait          init
     0       0     -1      0  3  0x10010200  scheduler     swapper
ddb> show all locks
No such command
ddb> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11041  12118K   12361K 166960K     13622        0
            pcb    17     16K      18K 166960K       202        0
         rtable   201      8K       9K 166960K       549        0
             pf    29     12K      15K 166960K       137        0
         ifaddr    35      6K       7K 166960K       104        0
        ifgroup    46      2K       2K 166960K       176        0
         sysctl     4      1K       9K 166960K        16        0
       counters    32     17K      18K 166960K       101        0
       ioctlops     0      0K       4K 166960K       146        0
            iov     0      0K      16K 166960K        51        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1424     90K      90K 166960K      2341        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      2K       6K 166960K        21        0
         VM map     2      1K       1K 166960K         2        0
            sem    12      0K       0K 166960K        64        0
        dirhash    12      2K       2K 166960K        27        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    16     57K     110K 166960K      1076        0
          sigio     0      0K       0K 166960K        16        0
           proc    60     59K      91K 166960K       641        0
        subproc    72      4K       4K 166960K        90        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K       225        0
       in_multi    74      5K       7K 166960K       164        0
    ether_multi     1      0K       0K 166960K        11        0
            mrt     1      0K       0K 166960K         3        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys    91    413K     413K 166960K        91        0
           exec     0      0K       1K 166960K       523        0
   fusefs mount     1     32K      32K 166960K         1        0
     pfkey data     0      0K       0K 166960K         5        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   217    135K     159K 166960K     12352        0
       UVM aobj    19      6K       8K 166960K        22        0
     pinsyscall    38     76K      90K 166960K      2235        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     0      0K       0K 166960K        47        0
            NDP    10      0K       2K 166960K        77        0
           temp    76   8676K    8756K 166960K     36329        0
         kqueue    14     22K      32K 166960K       243        0
      SYN cache     2      8K      16K 166960K         3        0
ddb> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
rtpcb      120      140    0      137     2     0     2     2     0     8    1
rtentry    136      162    0       83     4     0     4     4     0     8    0
unpcb      144      869    0      854     6     0     6     6     0     8    5
syncache   336       11    0       11     2     1     1     1     0     8    1
tcpqe       32        2    0        2     1     0     1     1     0     8    1
tcpcb      736      391    0      386     4     0     4     4     0     8    3
arp         96       31    0       13     1     0     1     1     0     8    0
ipq         40        9    0        8     1     0     1     1     0     8    0
ipqe        40       14    0       13     1     0     1     1     0     8    0
inpcb      328     1180    0     1171    10     0    10    10     0     8    8
ip6q        72        1    0        1     1     0     1     1     0     8    1
ip6af       40        1    0        1     1     0     1     1     0     8    1
nd6        112       35    0       18     1     0     1     1     0     8    0
pkpcb       40       12    0       12     1     0     1     1     0     8    1
kcovpl      48       10    0        2     1     0     1     1     0     8    0
ppxss      1072      56    0       56     1     0     1     1     0     8    1
pppxif     1384       3    0        3     1     0     1     1     0     8    1
pfstscr     40        1    0        1     1     0     1     1     0     8    1
pfstkey    128        1    0        1     1     0     1     1     0     8    1
pfstate    384        1    0        1     1     0     1     1     0     8    1
pfrule     1360       1    0        1     1     0     1     1     0     8    1
art_heap8  4096       3    0        0     3     0     3     3     0     8    0
art_heap4  256      624    0      275    29     0    29    29     0     8    4
art_table   40      627    0      275     5     0     5     5     0     8    0
art_node    32      161    0       89     1     0     1     1     0     8    0
sysvmsgpl   40        8    0        7     1     0     1     1     0     8    0
semupl     112        1    0        1     1     0     1     1     0     8    1
semapl     112       61    0       51     1     0     1     1     0     8    0
shmpl      112       15    0        1     1     0     1     1     0     8    0
dirhash    1024      27    0       10     3     0     3     3     0     8    0
dino2pl    256     3363    0     1870    95     0    95    95     0     8    0
ffsino     256     3363    0     1870    95     0    95    95     0     8    0
nchpl      144     4830    0     3137    64     0    64    64     0     8    0
rtmask      32       10    0       10     1     0     1     1     0     8    1
vnodes     216     4042    0        0   225     0   225   225     0     8    0
vnodes: pool(0xffffffff839671e0:vnodes): page inconsistency: page 0x0; at page head addr 0xfffffd806b952f90 (p 0xfffffd806b952000)
namei      1024   16695    0    16695     2     1     1     2     0     8    1
vcpupl     3904       3    0        1     1     0     1     1     0     8    0
vmpool     808        4    0        2     1     0     1     1     0     8    0
kstatmem   264      114    0       94     2     0     2     2     0     8    0
scsiplug    72        4    0        4     1     0     1     1     0     8    1
scxspl     216    15307    0    15307     9     1     8     8     1     8    8
plimitpl   152      236    0      220     1     0     1     1     0     8    0
sigapl     424     1386    0     1324     8     0     8     8     0     8    0
knotepl    120    41587    0    41539    20     9    11    16     0     8    8
kqueuepl   184      325    0      314     1     0     1     1     0     8    0
pipepl     304      184    0      157     3     0     3     3     0     8    0
fdescpl    448     1349    0     1320     4     0     4     4     0     8    0
filepl     120     8441    0     8232    13     0    13    13     0     8    5
lockfpl    104      258    0      256     1     0     1     1     0     8    0
lockfspl    48      113    0      111     1     0     1     1     0     8    0
sessionpl  144       28    0       20     1     0     1     1     0     8    0
pgrppl      48       80    0       64     1     0     1     1     0     8    0
ucredpl    104     1165    0     1153     1     0     1     1     0     8    0
zombiepl   144     2147    0     2147     2     1     1     1     0     8    1
processpl  1152    1387    0     1324     5     0     5     5     0     8    0
procpl     664     3199    0     3126     8     0     8     8     0     8    0
sosppl     176       10    0        9     1     0     1     1     0     8    0
sockpl     552     2235    0     2208    21    10    11    15     0     8    8
mcl64k     65536     80    0       80     1     0     1     1     0     8    1
mcl16k     16384      5    0        5     1     0     1     1     0     8    1
mcl12k     12288      2    0        2     1     0     1     1     0     8    1
mcl9k      9216       1    0        1     1     0     1     1     0     8    1
mcl8k      8192      13    0       13     2     1     1     1     0     8    1
mcl4k      4096    3827    0     3772    15     7     8    15     0     8    0
mcl2k      2048    1518    0     1515     9     0     9     9     0     8    8
mtagpl      96       18    0       13     2     1     1     1     0     8    0
mbufpl     256    16833    0    16679    25     2    23    24     0     8    8
bufpl      280     4546    0      137   315     0   315   315     0     8    0
anonpl      24   193769    0   190778    47     2    45    45     0   187   17
amapchunkpl 152   41173    0    40741    34     0    34    34     0   158   14
amappl16   200     2875    0     2844    17     6    11    14     0     8    8
amappl15   192        8    0        8     1     1     0     1     0     8    0
amappl14   184       11    0       11     1     1     0     1     0     8    0
amappl13   176      455    0      454     1     0     1     1     0     8    0
amappl12   168     1718    0     1681     2     0     2     2     0     8    0
amappl11   160        2    0        2     1     1     0     1     0     8    0
amappl10   152       69    0       59     1     0     1     1     0     8    0
amappl9    144      260    0      259     1     0     1     1     0     8    0
amappl8    136       22    0       21     1     0     1     1     0     8    0
amappl7    128       85    0       84     1     0     1     1     0     8    0
amappl6    120      290    0      278     1     0     1     1     0     8    0
amappl5    112       88    0       80     1     0     1     1     0     8    0
amappl4    104      415    0      392     1     0     1     1     0     8    0
amappl3     96     6961    0     6880     3     0     3     3     0     8    0
amappl2     88     1514    0     1445     2     0     2     2     0     8    0
amappl1     80    14566    0    14034    15     0    15    15     0     8    2
amappl      88    11395    0    11245     5     0     5     5     0    92    0
uvmvnodes   80      117    0        0     3     0     3     3     0     8    0
dma32768   32768      1    0        1     1     0     1     1     0     8    1
dma4096    4096       1    0        1     1     1     0     1     0     8    0
dma1024    1024       2    0        1     1     0     1     1     0     8    0
dma256     256        6    0        6     1     1     0     1     0     8    0
dma128     128      254    0      254     2     1     1     1     0     8    1
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       21    0        3     1     0     1     1     0     8    0
uaddrrnd    24     1348    0     1320     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24     1348    0     1320     1     0     1     1     0     8    0
vmmpekpl   168    13058    0    13005     3     0     3     3     0     8    0
vmmpepl    168    93009    0    91284    93     0    93    93     0   357    8
vmsppl     368     1347    0     1320     4     0     4     4     0     8    1
rwobjpl     40    26766    0    25810    13     0    13    13     0     8    1
pdppl      4096    2711    0     2646   116    47    69    75     0     8    4
pvpl        32   576266    0   568362   113     0   113   113     0   265   28
pmappl     216     1351    0     1322     2     0     2     2     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      416    0       61    11     0    11    11     0     8    0
ddb> machine ddbcpu 0
No such command
ddb> trace
checkalias(fffffd806b3350f0,21700,0) at checkalias+0xb7 sys/kern/vfs_subr.c:574
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 getdevvp sys/kern/vfs_subr.c:-1 [inline]
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 sys/kern/vfs_subr.c:517
spec_open_clone(ffff80003c13f0b8) at spec_open_clone+0x1e2 sys/kern/spec_vnops.c:713
spec_open(ffff80003c13f0b8) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd806f4b8030,9,fffffd8007bfd750,ffff80002a7762a0) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c13f300,9,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a7762a0,ffffff9c,200000000080,8,0,ffff80003c13f4a0) at doopenat+0x34d sys/kern/vfs_syscalls.c:1138
syscall(ffff80003c13f550) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c13f550) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x689c533c320, count: -9
ddb> machine ddbcpu 1
No such command
ddb> trace
checkalias(fffffd806b3350f0,21700,0) at checkalias+0xb7 sys/kern/vfs_subr.c:574
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 getdevvp sys/kern/vfs_subr.c:-1 [inline]
cdevvp(21700,ffff80003c13efe0) at cdevvp+0xd2 sys/kern/vfs_subr.c:517
spec_open_clone(ffff80003c13f0b8) at spec_open_clone+0x1e2 sys/kern/spec_vnops.c:713
spec_open(ffff80003c13f0b8) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd806f4b8030,9,fffffd8007bfd750,ffff80002a7762a0) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c13f300,9,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a7762a0,ffffff9c,200000000080,8,0,ffff80003c13f4a0) at doopenat+0x34d sys/kern/vfs_syscalls.c:1138
syscall(ffff80003c13f550) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c13f550) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x689c533c320, count: -9

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/25 01:20 openbsd 12762e433761 40acda8a .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: checkalias
* Struck through repros no longer work on HEAD.