Extracting prog: 7m52.635204168s
Minimizing prog: 33m53.878002007s
Simplifying prog options: 18m37.470258946s
Extracting C: 5m15.312940567s
Simplifying C: 0s


extracting reproducer from 1 programs
testing a last program of every proc
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): sendmsg$nl_route-syz_emit_vhci-syz_emit_vhci
detailed listing:
executing program 0:
sendmsg$nl_route(0xffffffffffffffff, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)={0x0, 0x3c}}, 0x0)
syz_emit_vhci(&(0x7f0000000000)=ANY=[@ANYBLOB="043e751d"], 0x24)
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program did not crash
single: failed to extract reproducer
single: executing 1 programs separately with timeout 6m0s
testing program (duration=6m0s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): sendmsg$nl_route-syz_emit_vhci-syz_emit_vhci
detailed listing:
executing program 0:
sendmsg$nl_route(0xffffffffffffffff, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)={0x0, 0x3c}}, 0x0)
syz_emit_vhci(&(0x7f0000000000)=ANY=[@ANYBLOB="043e751d"], 0x24)
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
single: successfully extracted reproducer
found reproducer with 3 syscalls
minimizing guilty program
testing program (duration=7m52.369667962s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): sendmsg$nl_route-syz_emit_vhci
detailed listing:
executing program 0:
sendmsg$nl_route(0xffffffffffffffff, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)={0x0, 0x3c}}, 0x0)
syz_emit_vhci(&(0x7f0000000000)=ANY=[@ANYBLOB="043e751d"], 0x24)

program did not crash
testing program (duration=7m52.369667962s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): sendmsg$nl_route-syz_emit_vhci
detailed listing:
executing program 0:
sendmsg$nl_route(0xffffffffffffffff, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)={0x0, 0x3c}}, 0x0)
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
testing program (duration=7m52.369667962s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
testing program (duration=7m52.369667962s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(0x0, 0x22)

program did not crash
testing program (duration=7m52.369667962s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB], 0x22)

program did not crash
extracting C reproducer
testing compiled C program (duration=7m52.369667962s, {Threaded:true Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
program crashed: no output from test machine
a never seen crash title: no output from test machine, ignore
simplifying guilty program options
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
extracting C reproducer
testing compiled C program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:6 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
program crashed: no output from test machine
a never seen crash title: no output from test machine, ignore
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
extracting C reproducer
testing compiled C program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
program crashed: no output from test machine
a never seen crash title: no output from test machine, ignore
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
validation run: crashed=true
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
validation run: crashed=true
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
validation run: crashed=true
reproducing took 1h16m36.132210121s
repro crashed as (corrupted=true):
Kernel panic - not syncing: hung_task: blocked tasks
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 vpanic+0x552/0x970 kernel/panic.c:650
 panic+0xd1/0xe0 kernel/panic.c:787
 check_hung_uninterruptible_tasks kernel/hung_task.c:356 [inline]
 watchdog.cold+0x1fd/0x234 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled

report is corrupted, running repro again
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
report is corrupted, running repro again
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
report is corrupted, running repro again
testing program (duration=7m52.369667962s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_emit_vhci
detailed listing:
executing program 0:
syz_emit_vhci(&(0x7f0000000080)=ANY=[@ANYBLOB="043eff1b"], 0x22)

program crashed: kernel panic: hung_task: blocked tasks
final repro crashed as (corrupted=true):
Kernel panic - not syncing: hung_task: blocked tasks
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 vpanic+0x552/0x970 kernel/panic.c:650
 panic+0xd1/0xe0 kernel/panic.c:787
 check_hung_uninterruptible_tasks kernel/hung_task.c:356 [inline]
 watchdog.cold+0x1fd/0x234 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled