syzbot


pool: free list modified: fdescpl (2)

Status: fixed on 2022/06/27 15:33
Reported-by: syzbot+fca7e4fa773c90886819@syzkaller.appspotmail.com
Fix commit: dc399801d5c5 kqueue: Clear task when closing kqueue
First crash: 208d, last: 163d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd pool: free list modified: fdescpl 1 314d 314d 0/3 auto-closed as invalid on 2022/04/21 05:57
openbsd pool: free list modified: fdescpl (3) 3 44d 147d 0/3 upstream: reported on 2022/07/07 19:55

Sample crash report:
panic: pool_do_get: fdescpl free list modified: page 0xfffffd807f7d5000; item addr 0xfffffd807f7d57c0; offset 0x48=0xdeafbeaf
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*512364  30825      0         0x2          0    1K syz-executor2970415296
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff82602af8) at panic+0x177 sys/kern/subr_prf.c:202
pool_do_get(ffffffff82b766e0,9,ffff8000211be508) at pool_do_get+0x474 sys/kern/subr_pool.c:741
pool_get(ffffffff82b766e0,9) at pool_get+0xe9 sys/kern/subr_pool.c:584
fdcopy(ffff8000ffff0010) at fdcopy+0x44 fdinit sys/kern/kern_descrip.c:1072 [inline]
fdcopy(ffff8000ffff0010) at fdcopy+0x44 sys/kern/kern_descrip.c:1111
process_new(ffff8000ffff7a50,ffff8000ffff0010,1) at process_new+0x13b sys/kern/kern_fork.c:259
fork1(ffff800021132fc8,1,ffffffff814b49c0,0,ffff8000211be740,0) at fork1+0x30b sys/kern/kern_fork.c:383
syscall(ffff8000211be7b0) at syscall+0x489 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff8000211be7b0) at syscall+0x489 sys/arch/amd64/amd64/trap.c:585
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f7ffffed970, 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{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
*cpu1: pool_do_get: fdescpl free list modified: page 0xfffffd807f7d5000; item addr 0xfffffd807f7d57c0; offset 0x48=0xdeafbeaf
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff82602af8) at panic+0x177 sys/kern/subr_prf.c:202
pool_do_get(ffffffff82b766e0,9,ffff8000211be508) at pool_do_get+0x474 sys/kern/subr_pool.c:741
pool_get(ffffffff82b766e0,9) at pool_get+0xe9 sys/kern/subr_pool.c:584
fdcopy(ffff8000ffff0010) at fdcopy+0x44 fdinit sys/kern/kern_descrip.c:1072 [inline]
fdcopy(ffff8000ffff0010) at fdcopy+0x44 sys/kern/kern_descrip.c:1111
process_new(ffff8000ffff7a50,ffff8000ffff0010,1) at process_new+0x13b sys/kern/kern_fork.c:259
fork1(ffff800021132fc8,1,ffffffff814b49c0,0,ffff8000211be740,0) at fork1+0x30b sys/kern/kern_fork.c:383
syscall(ffff8000211be7b0) at syscall+0x489 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff8000211be7b0) at syscall+0x489 sys/arch/amd64/amd64/trap.c:585
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f7ffffed970, count: -9
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff8000211be350
rbx               0xffff800020cd9c5f
rdx                            0x3fd
rcx                                0
rax                             0x7e
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x62a06b729b9b1a9d
r11               0xcf40283f726f2a7b
r12               0xffff800020cd9a60
r13                                0
r14                                0
r15                              0x1
rip               0xffffffff81995478    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff8000211be340
ss                              0x10
db_enter+0x18:  addq    $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor2970415296) pid=512364 stat=onproc
    flags process=2<EXEC> proc=0
    pri=17, usrpri=86, nice=20
    forw=0xffffffffffffffff, list=0xffff8000211337a8,0xffffffff82b7abc8
    process=0xffff8000ffff0010 user=0xffff8000211b9000, vmspace=0xfffffd807effd730
    estcpu=36, cpticks=3, pctcpu=0.1
    user=0, sys=1, intr=0
ddb{1}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
*30825  512364  97626      0  7         0x2                syz-executor2970415296
 97626  508814  22923      0  3    0x10008a  sigsusp       ksh
 22923  341307  93770      0  3        0x9a  kqread        sshd
 84207  150102      1      0  3    0x100083  ttyin         getty
 93770  364531      1      0  3        0x88  kqread        sshd
 14175  287577  34806     73  3   0x1100090  kqread        syslogd
 34806  314123      1      0  3    0x100082  netio         syslogd
 70881  308436      1      0  3    0x100080  kqread        resolvd
 43833  189038  90895     77  3    0x100092  kqread        dhcpleased
 73923  304225  90895     77  3    0x100092  kqread        dhcpleased
 90895   28238      1      0  3        0x80  kqread        dhcpleased
 89758  432654      0      0  3     0x14200  bored         smr
 68338  411667      0      0  3     0x14200  pgzero        zerothread
 39311  152099      0      0  3     0x14200  aiodoned      aiodoned
 73560    3058      0      0  3     0x14200  syncer        update
  5666  129954      0      0  3     0x14200  cleaner       cleaner
 95815  475287      0      0  3     0x14200  reaper        reaper
 87660  256744      0      0  3     0x14200  pgdaemon      pagedaemon
 33875  301582      0      0  3     0x14200  bored         viomb
   705  326943      0      0  3  0x40014200  acpi0         acpi0
 48456  485291      0      0  3  0x40014200                idle1
  2772   80490      0      0  3     0x14200  bored         softnet
 15102  492063      0      0  3     0x14200  bored         softnet
 46594   37378      0      0  3     0x14200  bored         softnet
 84943  322056      0      0  3     0x14200  bored         softnet
 83563  267552      0      0  3     0x14200  fdlock        systqmp
 48604  402692      0      0  3     0x14200  bored         systq
 94836  232884      0      0  3  0x40014200  bored         softclock
 17075  374451      0      0  7  0x40014200                idle0
     1   75789      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{1}> show all locks
CPU 1:
exclusive mutex fdescpl r = 0 (0xffffffff82b766f0)
#0  witness_lock+0x44d
#1  mtx_enter_try+0x100
#2  mtx_enter+0x4b sys/kern/kern_lock.c:266
#3  pool_get+0xbd sys/kern/subr_pool.c:581
#4  fdcopy+0x44 fdinit sys/kern/kern_descrip.c:1072 [inline]
#4  fdcopy+0x44 sys/kern/kern_descrip.c:1111
#5  process_new+0x13b sys/kern/kern_fork.c:259
#6  fork1+0x30b sys/kern/kern_fork.c:383
#7  syscall+0x489 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#7  syscall+0x489 sys/arch/amd64/amd64/trap.c:585
#8  Xsyscall+0x128
Process 30825 (syz-executor2970415296) thread 0xffff800021132fc8 (512364)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82b9f538)
#0  witness_lock+0x44d
#1  syscall+0x3ef mi_syscall sys/sys/syscall_mi.h:93 [inline]
#1  syscall+0x3ef sys/arch/amd64/amd64/trap.c:585
#2  Xsyscall+0x128
exclusive mutex fdescpl r = 0 (0xffffffff82b766f0)
#0  witness_lock+0x44d
#1  mtx_enter_try+0x100
#2  mtx_enter+0x4b sys/kern/kern_lock.c:266
#3  pool_get+0xbd sys/kern/subr_pool.c:581
#4  fdcopy+0x44 fdinit sys/kern/kern_descrip.c:1072 [inline]
#4  fdcopy+0x44 sys/kern/kern_descrip.c:1111
#5  process_new+0x13b sys/kern/kern_fork.c:259
#6  fork1+0x30b sys/kern/kern_fork.c:383
#7  syscall+0x489 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#7  syscall+0x489 sys/arch/amd64/amd64/trap.c:585
#8  Xsyscall+0x128
Process 83563 (systqmp) thread 0xffff8000210e82a0 (267552)
shared rwlock systqmp r = 0 (0xffffffff829b2810)
#0  witness_lock+0x44d
#1  taskq_thread+0xca sys/kern/kern_task.c:445
#2  proc_trampoline+0x1c
ddb{1}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 10146   6388K    6420K  78643K     11236        0
            pcb    13      8K       8K  78643K        13        0
         rtable    58      1K       2K  78643K       104        0
         ifaddr    24      7K       7K  78643K        24        0
       counters    40     33K      33K  78643K        40        0
       ioctlops     0      0K       2K  78643K        25        0
          mount     1      1K       1K  78643K         1        0
            log     0      0K       0K  78643K         5        0
         vnodes  1166     73K      73K  78643K      1179        0
      UFS quota     1     32K      32K  78643K         1        0
      UFS mount     5     36K      36K  78643K         5        0
            shm     2      1K       1K  78643K         2        0
         VM map     2      1K       1K  78643K         2        0
            sem     2      0K       0K  78643K         2        0
        dirhash    12      2K       2K  78643K        12        0
           ACPI  1697    195K     286K  78643K     12548        0
      file desc     1      0K       3K  78643K     20701        0
           proc    55     78K      79K  78643K       226        0
    NFS srvsock     1      0K       0K  78643K         1        0
     NFS daemon     1     16K      16K  78643K         1        0
       in_multi    11      0K       0K  78643K        11        0
    ether_multi     1      0K       0K  78643K         1        0
    ISOFS mount     1     32K      32K  78643K         1        0
  MSDOSFS mount     1     16K      16K  78643K         1        0
           ttys    25    122K     122K  78643K        25        0
           exec     0      0K       2K  78643K       391        0
            tdb     3      0K       0K  78643K         3        0
        pagedep     1      8K       8K  78643K         1        0
       inodedep     1     32K      32K  78643K         1        0
         newblk     1      0K       0K  78643K         1        0
        VM swap     7     26K      26K  78643K         7        0
       UVM amap    55     11K      11K  78643K     15226        0
       UVM aobj     3      2K       2K  78643K         3        0
        memdesc     1      4K       4K  78643K         1        0
    crypto data     1      1K       1K  78643K         1        0
            NDP     3      0K       0K  78643K         3        0
           temp    18   4713K    4777K  78643K     16069        0
         kqueue    18     30K      30K  78643K      6924        0
      SYN cache     2     16K      16K  78643K         2        0
ddb{1}> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
plcache    128       22    0        0     1     0     1     1     0     8    0
rtpcb      120       17    0       14     1     0     1     1     0     8    0
rtentry    112       23    0        1     1     0     1     1     0     8    0
unpcb      136     6933    0     6920     1     0     1     1     0     8    0
syncache   296        5    0        5     2     2     0     1     0     8    0
tcpcb      736        8    0        5     1     0     1     1     0     8    0
arp        120        2    0        0     1     0     1     1     0     8    0
inpcb      312       25    0       19     1     0     1     1     0     8    0
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256       97    0        0     7     0     7     7     0     8    0
art_table   32       98    0        0     1     0     1     1     0     8    0
art_node    16       22    0        2     1     0     1     1     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     8318    0     6938    87     0    87    87     0     8    0
ffsino     272     8318    0     6938    93     0    93    93     0     8    1
nchpl      144    15405    0    13848    58     0    58    58     0     8    0
uvmvnodes   80     5926    0        0   121     0   121   121     0     8    0
vnodes     224     5926    0        0   349     0   349   349     0     8    0
namei      1024   31779    0    31779     2     1     1     1     0     8    1
percpumem   16       32    0        0     1     0     1     1     0     8    0
kstatmem   264        6    0        0     1     0     1     1     0     8    0
scxspl     216    45466    0    45466    13    12     1     8     0     8    1
plimitpl   152       16    0        9     1     0     1     1     0     8    0
sigapl     424     7195    0     7165     4     0     4     4     0     8    0
knotepl    120       50    0        0     2     0     2     2     0     8    0
kqueuepl   216     6920    0     6906     1     0     1     1     0     8    0
pipepl     336   448579    0   448576     7     1     6     6     0     8    5
fdescpl    496     7178    0     7165     3     1     2     3     0     8    0
pool(0xffffffff82b766e0:fdescpl): page inconsistency: page 0xfffffd807f7d5000; 2 on list, 5 missing, 8 items per page
filepl     152   918743    0   918690     8     0     8     8     0     8    5
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       18    0        9     1     0     1     1     0     8    0
pgrppl      48       18    0        9     1     0     1     1     0     8    0
ucredpl     96       64    0       54     1     0     1     1     0     8    0
zombiepl   144     7165    0     7165     2     1     1     1     0     8    1
processpl  1064    7196    0     7165     3     0     3     3     0     8    0
procpl     672     7196    0     7165     3     0     3     3     0     8    0
sockpl     480     6975    0     6953     3     0     3     3     0     8    0
mcl8k      8192       5    0        0     1     0     1     1     0     8    0
mcl4k      4096       2    0        0     1     0     1     1     0     8    0
mcl2k      2048      64    0        0     7     0     7     7     0     8    0
mtagpl      96        2    0        0     1     0     1     1     0     8    0
mbufpl     256      129    0        0     7     0     7     7     0     8    0
bufpl      288     8839    0     2624   445     0   445   445     0     8    0
anonpl      24   174969    0   173115    14     2    12    13     0   186    0
amapchunkpl 152   37096    0    37006     5     1     4     5     0   158    0
amappl16   200     6985    0     6980     1     0     1     1     0     8    0
amappl13   176       32    0       31     2     1     1     1     0     8    0
amappl12   168        3    0        3     2     2     0     1     0     8    0
amappl11   160       60    0       47     1     0     1     1     0     8    0
amappl10   152        2    0        2     1     1     0     1     0     8    0
amappl9    144      488    0      485     1     0     1     1     0     8    0
amappl8    136      334    0      333     2     1     1     1     0     8    0
amappl7    128       48    0       45     1     0     1     1     0     8    0
amappl6    120       94    0       83     1     0     1     1     0     8    0
amappl5    112       82    0       74     1     0     1     1     0     8    0
amappl4    104     7469    0     7448     1     0     1     1     0     8    0
amappl3     96     7237    0     7217     1     0     1     1     0     8    0
amappl2     88      417    0      379     1     0     1     1     0     8    0
amappl1     80    89513    0    89135    10     1     9     9     0     8    0
amappl      88    14971    0    14934     1     0     1     1     0    92    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     7178    0     7165     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24     7178    0     7165     1     0     1     1     0     8    0
vmmpekpl   168  1820641    0  1820627     1     0     1     1     0     8    0
vmmpepl    168   266439    0   265647    41     4    37    38     0   357    0
vmsppl     368     7177    0     7165     2     0     2     2     0     8    0
rwobjpl     56    39166    0    32711    91     0    91    91     0     8    0
pdppl      4096   14363    0    14330    53    18    35    41     0     8    2
pvpl        32   801313    0   797580    37     5    32    33     0   265    0
pmappl     248     7177    0     7165     2     1     1     2     0     8    0
extentpl    40       58    0       38     1     0     1     1     0     8    0
phpool     112      721    0       22    20     0    20    20     0     8    0
ddb{1}> machine ddbcpu 0
Stopped at      x86_ipi_db+0x1a:        addq    $0x8,%rsp
x86_ipi_db(ffffffff82999ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:393
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
__mp_lock(ffffffff82b9f330) at __mp_lock+0x122 __mp_lock_spin sys/kern/kern_lock.c:116 [inline]
__mp_lock(ffffffff82b9f330) at __mp_lock+0x122 sys/kern/kern_lock.c:147
softintr_dispatch(0) at softintr_dispatch+0x4e sys/arch/amd64/amd64/softintr.c:88
Xsoftclock() at Xsoftclock+0x1f
acpicpu_idle() at acpicpu_idle+0x312 sys/dev/acpi/acpicpu.c:1206
sched_idle(ffffffff82999ff0) at sched_idle+0x417 sys/kern/kern_sched.c:178
end trace frame: 0x0, count: 7
ddb{0}> trace
x86_ipi_db(ffffffff82999ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:393
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
__mp_lock(ffffffff82b9f330) at __mp_lock+0x122 __mp_lock_spin sys/kern/kern_lock.c:116 [inline]
__mp_lock(ffffffff82b9f330) at __mp_lock+0x122 sys/kern/kern_lock.c:147
softintr_dispatch(0) at softintr_dispatch+0x4e sys/arch/amd64/amd64/softintr.c:88
Xsoftclock() at Xsoftclock+0x1f
acpicpu_idle() at acpicpu_idle+0x312 sys/dev/acpi/acpicpu.c:1206
sched_idle(ffffffff82999ff0) at sched_idle+0x417 sys/kern/kern_sched.c:178
end trace frame: 0x0, count: -8
ddb{0}> machine ddbcpu 1
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff82602af8) at panic+0x177 sys/kern/subr_prf.c:202
pool_do_get(ffffffff82b766e0,9,ffff8000211be508) at pool_do_get+0x474 sys/kern/subr_pool.c:741
pool_get(ffffffff82b766e0,9) at pool_get+0xe9 sys/kern/subr_pool.c:584
fdcopy(ffff8000ffff0010) at fdcopy+0x44 fdinit sys/kern/kern_descrip.c:1072 [inline]
fdcopy(ffff8000ffff0010) at fdcopy+0x44 sys/kern/kern_descrip.c:1111
process_new(ffff8000ffff7a50,ffff8000ffff0010,1) at process_new+0x13b sys/kern/kern_fork.c:259
fork1(ffff800021132fc8,1,ffffffff814b49c0,0,ffff8000211be740,0) at fork1+0x30b sys/kern/kern_fork.c:383
syscall(ffff8000211be7b0) at syscall+0x489 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff8000211be7b0) at syscall+0x489 sys/arch/amd64/amd64/trap.c:585
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f7ffffed970, count: 6
ddb{1}> 

Crashes (6):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-openbsd-setuid 2022/06/19 14:17 openbsd 75a44452e183 8f633d84 .config log report syz C pool: free list modified: fdescpl
ci-openbsd-multicore 2022/06/21 16:42 openbsd 6e1ff440574c 0fc5c330 .config log report pool: free list modified: fdescpl
ci-openbsd-setuid 2022/06/19 12:54 openbsd 75a44452e183 8f633d84 .config log report pool: free list modified: fdescpl
ci-openbsd-setuid 2022/06/18 23:55 openbsd 7a05b9df39f3 8f633d84 .config log report pool: free list modified: fdescpl
ci-openbsd-setuid 2022/05/10 04:52 openbsd ddfdd69b7d10 8b277b8e .config log report pool: free list modified: fdescpl
ci-openbsd-setuid 2022/05/07 18:19 openbsd a7a028b08355 e60b1103 .config log report pool: free list modified: fdescpl
* Struck through repros no longer work on HEAD.