panic: ffs_blkfree: freeing free frag (2)

Status: upstream: reported on 2026/08/05 04:41
Reported-by: syzbot+2b3c7f8a2b4e67cdd315@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 panic: ffs_blkfree: freeing free frag 2 1 694d 694d 0/4 auto-obsoleted due to no activity on 2024/12/24 07:53

Sample crash report:
panic: ffs_blkfree: freeing free frag
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*418394  95630      0  0x10000002          0    0  sshd
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8348d3eb) at panic+0x1cf sys/kern/subr_prf.c:198
ffs_blkfree(fffff1006fb74300,91405,800) at ffs_blkfree+0xce9 sys/ufs/ffs/ffs_alloc.c:1259
ffs_truncate(fffff1006fb74300,0,0,fffff10007ffd9c0) at ffs_truncate+0x1390 sys/ufs/ffs/ffs_inode.c:325
ufs_setattr(ffff80002a7b7670) at ufs_setattr+0x8e0 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffff100678a9ce8,ffff80002a7b76f0,fffff10007ffd9c0,ffff80002a772fa0) at VOP_SETATTR+0x112 sys/kern/vfs_vops.c:210
vn_open(ffff80002a7b78d0,602,1a4) at vn_open+0x6b0 sys/kern/vfs_vnops.c:180
doopenat(ffff80002a772fa0,ffffff9c,c92ffa0140,601,1b6,0,f0b8f6c61743b05c) at doopenat+0x352 sys/kern/vfs_syscalls.c:1163
sys_open(ffff80002a772fa0,ffff80002a7b7b70,ffff80002a7b7ac0) at sys_open+0x59 sys/kern/vfs_syscalls.c:1065
syscall(ffff80002a7b7b70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a7b7b70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x724c3a85dee0, count: 4
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: ffs_blkfree: freeing free frag
ddb> show kasan
No such command
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8348d3eb) at panic+0x1cf sys/kern/subr_prf.c:198
ffs_blkfree(fffff1006fb74300,91405,800) at ffs_blkfree+0xce9 sys/ufs/ffs/ffs_alloc.c:1259
ffs_truncate(fffff1006fb74300,0,0,fffff10007ffd9c0) at ffs_truncate+0x1390 sys/ufs/ffs/ffs_inode.c:325
ufs_setattr(ffff80002a7b7670) at ufs_setattr+0x8e0 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffff100678a9ce8,ffff80002a7b76f0,fffff10007ffd9c0,ffff80002a772fa0) at VOP_SETATTR+0x112 sys/kern/vfs_vops.c:210
vn_open(ffff80002a7b78d0,602,1a4) at vn_open+0x6b0 sys/kern/vfs_vnops.c:180
doopenat(ffff80002a772fa0,ffffff9c,c92ffa0140,601,1b6,0,f0b8f6c61743b05c) at doopenat+0x352 sys/kern/vfs_syscalls.c:1163
sys_open(ffff80002a772fa0,ffff80002a7b7b70,ffff80002a7b7ac0) at sys_open+0x59 sys/kern/vfs_syscalls.c:1065
syscall(ffff80002a7b7b70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a7b7b70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x724c3a85dee0, count: -11
ddb> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80002a7b7280
rbx                           0x2560    __ALIGN_SIZE+0x1560
rdx                                0
rcx                                0
rax               0xffff80002a772fa0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x27f61003fdf2938c
r11                0x3708f4ff3aa434b
r12                                0
r13                          0x90255    acpi_pdirpa+0x7c0c6
r14                                0
r15                              0x1
rip               0xffffffff8330a1a5    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff80002a7b7270
ss                              0x10
db_enter+0x25:  addq    $0x8,%rsp
ddb> show proc
PROC (sshd) tid=418394 pid=95630 tcnt=1 stat=onproc
    flags process=10000002<EXEC,WAITEVENT> proc=0
    runpri=17, usrpri=51, slppri=17, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80002a772a70,0xffff80002a773248
    process=0xffff80002a79f610 user=0xffff80002a7b2000, vmspace=0xfffff1007661da18
    estcpu=1, cpticks=3, pctcpu=0.0, user=0, sys=2, intr=0
ddb> ps
   PID     TID   PPID   UID  S      PRLAGS     PFLAGS WAIT      COMMAND
 38066  410878  75320     0  2           0          0           syz-executor
 38066  482693  75320     0  2           0  0x4000000           syz-executor
 63900  381196  76351     0  2           0          0           syz-executor
 64959  463962      1     0  3           0       0x80 nanoslp   init
 11968  382064  57852     0  3        0x11       0x80 nanoslp   syz-executor
 11968  401903  57852     0  3        0x11  0x4000080 fsleep    syz-executor
 11968  491535  57852     0  2        0x11  0x4000000           syz-executor
 11968  379541  57852     0  3        0x11  0x4000080 fsleep    syz-executor
 64510   42329  21620     0  2           0          0           syz-executor
 64510  514353  21620     0  3           0  0x4000080 fsleep    syz-executor
 65367  265929  94507     0  3      0x1000  0x4080000 smrbar    syz-executor
 65367   47514  94507     0  3      0x1000  0x4002000 suspend   syz-executor
 15314   40111  11987 60929  3        0x10       0x80 nanoslp   syz-executor
 15314  281021  11987 60929  3        0x10  0x4000080 fsleep    syz-executor
 76351  191820  69091     0  2         0x2          0           syz-executor
  5257   21410  69091     0  3         0x2       0x80 nanoslp   syz-executor
 11987  102010  69091     0  3         0x2       0x80 nanoslp   syz-executor
 75320  442030  69091     0  3         0x2       0x80 nanoslp   syz-executor
 89154  412896  69091     0  2         0x2          0           syz-executor
 57852  418624  69091     0  3         0x2       0x80 nanoslp   syz-executor
 21620  374677  69091     0  3         0x2       0x80 nanoslp   syz-executor
 94507  282065  69091     0  3         0x2       0x80 nanoslp   syz-executor
 69091  516889      1     0  3         0x2       0x80 kqread    syz-executor
*95630  418394      1     0  7  0x10000002          0           sshd
 51484  146087  83960    73  3   0x1100010       0x80 kqread    syslogd
 83960  434526      1     0  3    0x100002       0x80 sbwait    syslogd
 58523   91563      1     0  3    0x100000       0x80 kqread    resolvd
 73582  252192  42675    77  3    0x100012       0x80 kqread    dhcpleased
 79468   43127  42675    77  3    0x100012       0x80 kqread    dhcpleased
 42675  470962      1     0  3           0       0x80 kqread    dhcpleased
 80907  109324      0     0  3     0x14000      0x200 bored     smr
 61104  316474      0     0  2     0x14000      0x200           zerothread
 79297   76410      0     0  3     0x14000      0x200 aiodoned  aiodoned
 99447   83818      0     0  3     0x14000      0x200 syncer    update
 56623  142315      0     0  3     0x14000      0x200 cleaner   cleaner
 57193  167900      0     0  3     0x14000      0x200 reaper    reaper
 43272   48417      0     0  3     0x14000      0x200 pgdaemon  pagedaemon
 90320  373657      0     0  3     0x14000      0x200 bored     viomb
 56109  332086      0     0  3     0x14000 0x40000200 acpi0     acpi0
 83149  186554      0     0  3     0x14000      0x200 bored     softnet0
 19837  415764      0     0  3     0x14000      0x200 bored     systqmp
 72900  175188      0     0  3     0x14000      0x200 bored     systq
 18835  308152      0     0  3     0x14000 0x40000200 tmoslp    softclock
 68271  228798      0     0  3     0x14000 0x40000200           idle0
     1  329672      0     0  3         0x2       0x80 wait      init
     0       0     -1     0  3     0x10000      0x200 scheduler swapper
ddb> show all locks
No such command
ddb> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11064  12110K   12280K 166960K     12334        0
            pcb    18     13K      14K 166960K       103        0
         rtable   253      8K       8K 166960K       400        0
             pf    34     13K      20K 166960K        68        0
         ifaddr    43      7K       7K 166960K        46        0
        ifgroup    55      2K       2K 166960K        60        0
         sysctl     3      1K       9K 166960K         9        0
       counters    34     17K      18K 166960K        37        0
       ioctlops     0      0K       4K 166960K        75        0
            iov     0      0K      12K 166960K        76        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1301     82K      82K 166960K      1481        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       9K 166960K         5        0
         VM map     2      1K       1K 166960K         2        0
            sem    12      0K       0K 166960K        17        0
        dirhash    12      2K       2K 166960K        15        0
           ACPI  1734    201K     291K 166960K     11964        0
      file desc    17     61K      97K 166960K       317        0
          sigio     0      0K       0K 166960K         4        0
           proc    51     50K     124K 166960K       510        0
        subproc    72      4K       4K 166960K        72        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K        27        0
       in_multi    99      6K       7K 166960K       106        0
    ether_multi     1      0K       0K 166960K         3        0
            mrt     0      0K       0K 166960K         6        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys   223    996K     996K 166960K       223        0
           exec     0      0K       1K 166960K       381        0
   fusefs mount     1     32K      32K 166960K         1        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   189    121K     152K 166960K      4599        0
       UVM aobj     7      2K       4K 166960K         8        0
     pinsyscall    32     64K      96K 166960K      1427        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     2      0K       0K 166960K        10        0
            NDP    12      0K       2K 166960K        29        0
           temp    36   9112K    9122K 166960K      4323        0
         kqueue    13     20K      28K 166960K        62        0
      SYN cache     2     16K      16K 166960K         2        0
ddb> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
rtpcb      120       51    0       47     1     0     1     1     0     8    0
rtentry    136      118    0        6     4     0     4     4     0     8    0
unpcb      144      156    0      140     1     0     1     1     0     8    0
syncache   336        6    0        6     2     1     1     1     0     8    1
tcpcb      736       82    0       78     4     3     1     4     0     8    0
arp         96       19    0        1     1     0     1     1     0     8    0
ipq         40        1    0        0     1     0     1     1     0     8    0
ipqe        40        1    0        0     1     0     1     1     0     8    0
inpcb      328      264    0      256     7     5     2     7     0     8    0
nd6        112       25    0        0     1     0     1     1     0     8    0
kcovpl      48        8    0        0     1     0     1     1     0     8    0
ppxss      1072       3    0        3     1     0     1     1     0     8    1
pfstscr     40        3    0        1     1     0     1     1     0     8    0
pfrktable  1344       2    0        2     1     1     0     1     0     8    0
pfanchor   1288       5    0        0     1     0     1     1     0     8    0
pftag       88        3    0        2     1     0     1     1     0     8    0
pfstitem    24        4    0        0     1     0     1     1     0     8    0
pfstkey    128        6    0        2     1     0     1     1     0     8    0
pfstate    384        3    0        1     1     0     1     1     0     8    0
pfrule     1360       5    0        5     1     1     0     1     0     8    0
art_heap8  4096       3    0        0     3     0     3     3     0     8    0
art_heap4  256      455    0        2    29     0    29    29     0     8    0
art_table   40      458    0        2     5     0     5     5     0     8    0
art_node    32      117    0       15     1     0     1     1     0     8    0
semupl     112        1    0        1     1     1     0     1     0     8    0
semapl      72       14    0        4     1     0     1     1     0     8    0
shmpl      112        5    0        1     1     0     1     1     0     8    0
dirhash    1024      19    0        2     3     0     3     3     0     8    0
dino2pl    256     1883    0      423    92     0    92    92     0     8    0
ffsino     256     1883    0      423    92     0    92    92     0     8    0
nchpl      144     2324    0      624    64     0    64    64     0     8    0
rtmask      32        2    0        2     1     0     1     1     0     8    1
vnodes     216     2033    0        0   113     0   113   113     0     8    0
namei      1024    7551    0     7550     2     1     1     1     0     8    0
acpiwqpl    32        1    0        1     1     0     1     1     1     8    1
kstatmem   264       27    0        2     2     0     2     2     0     8    0
scsiplug    72        2    0        2     1     1     0     1     0     8    0
scxspl     216     7841    0     7841     3     2     1     3     1     8    1
plimitpl   152      124    0      109     1     0     1     1     0     8    0
sigapl     424      615    0      575     6     1     5     6     0     8    0
knotepl    120    10785    0    10742    26    15    11    19     0     8    8
kqueuepl   184       61    0       50     1     0     1     1     0     8    0
pipepl     304      138    0      111     3     0     3     3     0     8    0
fdescpl    448      602    0      576     5     1     4     5     0     8    0
filepl     120     3031    0     2815    10     1     9     9     0     8    1
lockfpl    104       53    0       51     1     0     1     1     0     8    0
lockfspl    48       25    0       23     1     0     1     1     0     8    0
sessionpl  144       35    0       27     1     0     1     1     0     8    0
pgrppl      48       45    0       29     1     0     1     1     0     8    0
ucredpl    104      410    0      397     1     0     1     1     0     8    0
zombiepl   144      577    0      575     2     1     1     1     0     8    0
processpl  1152     615    0      575     4     0     4     4     0     8    0
procpl     664      891    0      843     6     1     5     6     0     8    0
sockpl     552      481    0      453     8     5     3     8     0     8    0
mcl64k     65536      5    0        5     2     1     1     1     0     8    1
mcl8k      8192       9    0        9     2     1     1     1     0     8    1
mcl4k      4096    2771    0     2721    14     7     7    14     0     8    0
mcl2k      2048     252    0      251     1     0     1     1     0     8    0
mextrefs    64      111    0      110     1     0     1     1     0     8    0
mtagpl      96        5    0        5     1     1     0     1     0     8    0
mbufpl     256     8088    0     7945    25     7    18    18     0     8    6
bufpl      272     2657    0      102   171     0   171   171     0     8    0
anonpl      24   108993    0   106420    46    19    27    46     0   187    0
amapchunkpl 152   13990    0    13590    32    11    21    32     0   158    1
amappl16   200     1644    0     1619    14    11     3    14     0     8    0
amappl15   192       24    0       24     1     1     0     1     0     8    0
amappl14   184      410    0      410     1     0     1     1     0     8    1
amappl13   176      145    0      138     1     0     1     1     0     8    0
amappl12   168      851    0      828     2     0     2     2     0     8    0
amappl11   160        6    0        6     1     1     0     1     0     8    0
amappl10   152       61    0       51     1     0     1     1     0     8    0
amappl9    144      275    0      274     1     0     1     1     0     8    0
amappl8    136      116    0      114     1     0     1     1     0     8    0
amappl7    128      146    0      136     1     0     1     1     0     8    0
amappl6    120      148    0      147     1     0     1     1     0     8    0
amappl5    112       88    0       83     1     0     1     1     0     8    0
amappl4    104      275    0      259     1     0     1     1     0     8    0
amappl3     96     2560    0     2470     4     1     3     4     0     8    0
amappl2     88      535    0      492     2     0     2     2     0     8    0
amappl1     80    11075    0    10721    14     2    12    14     0     8    1
amappl      88     3863    0     3725     5     0     5     5     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      254    0      254     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        7    0        1     1     0     1     1     0     8    0
uaddrrnd    24      602    0      576     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      602    0      576     1     0     1     1     0     8    0
vmmpekpl   168     6715    0     6680     2     0     2     2     0     8    0
vmmpepl    168    46723    0    45317    92    11    81    91     0   357    7
vmsppl     368      601    0      576     4     1     3     4     0     8    0
rwobjpl     40    15964    0    15206    13     2    11    13     0     8    0
pdppl      4096    1210    0     1152    96    30    66    82     0     8    8
pvpl        32   278859    0   271894   116    25    91   116     0   265   12
pmappl     216      601    0      576     3     0     3     3     0     8    0
extentpl    40       46    0       28     1     0     1     1     0     8    0
phpool     112      551    0       56    15     0    15    15     0     8    0
ddb> machine ddbcpu 0
No such command
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8348d3eb) at panic+0x1cf sys/kern/subr_prf.c:198
ffs_blkfree(fffff1006fb74300,91405,800) at ffs_blkfree+0xce9 sys/ufs/ffs/ffs_alloc.c:1259
ffs_truncate(fffff1006fb74300,0,0,fffff10007ffd9c0) at ffs_truncate+0x1390 sys/ufs/ffs/ffs_inode.c:325
ufs_setattr(ffff80002a7b7670) at ufs_setattr+0x8e0 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffff100678a9ce8,ffff80002a7b76f0,fffff10007ffd9c0,ffff80002a772fa0) at VOP_SETATTR+0x112 sys/kern/vfs_vops.c:210
vn_open(ffff80002a7b78d0,602,1a4) at vn_open+0x6b0 sys/kern/vfs_vnops.c:180
doopenat(ffff80002a772fa0,ffffff9c,c92ffa0140,601,1b6,0,f0b8f6c61743b05c) at doopenat+0x352 sys/kern/vfs_syscalls.c:1163
sys_open(ffff80002a772fa0,ffff80002a7b7b70,ffff80002a7b7ac0) at sys_open+0x59 sys/kern/vfs_syscalls.c:1065
syscall(ffff80002a7b7b70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a7b7b70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x724c3a85dee0, count: -11
ddb> machine ddbcpu 1
No such command
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8348d3eb) at panic+0x1cf sys/kern/subr_prf.c:198
ffs_blkfree(fffff1006fb74300,91405,800) at ffs_blkfree+0xce9 sys/ufs/ffs/ffs_alloc.c:1259
ffs_truncate(fffff1006fb74300,0,0,fffff10007ffd9c0) at ffs_truncate+0x1390 sys/ufs/ffs/ffs_inode.c:325
ufs_setattr(ffff80002a7b7670) at ufs_setattr+0x8e0 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffff100678a9ce8,ffff80002a7b76f0,fffff10007ffd9c0,ffff80002a772fa0) at VOP_SETATTR+0x112 sys/kern/vfs_vops.c:210
vn_open(ffff80002a7b78d0,602,1a4) at vn_open+0x6b0 sys/kern/vfs_vnops.c:180
doopenat(ffff80002a772fa0,ffffff9c,c92ffa0140,601,1b6,0,f0b8f6c61743b05c) at doopenat+0x352 sys/kern/vfs_syscalls.c:1163
sys_open(ffff80002a772fa0,ffff80002a7b7b70,ffff80002a7b7ac0) at sys_open+0x59 sys/kern/vfs_syscalls.c:1065
syscall(ffff80002a7b7b70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a7b7b70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x724c3a85dee0, count: -11
ddb> 

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/05 04:41 openbsd e4512c136ac0 52aa2820 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main panic: ffs_blkfree: freeing free frag
* Struck through repros no longer work on HEAD.