Bug 437523 - ksystemstats segfaults on start inLmSensorsPlugin::update()
Summary: ksystemstats segfaults on start inLmSensorsPlugin::update()
Status: RESOLVED FIXED
Alias: None
Product: plasma-systemmonitor
Classification: Applications
Component: general (show other bugs)
Version: 5.21.90
Platform: Kubuntu Linux
: NOR crash
Target Milestone: ---
Assignee: KSysGuard Developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-05-23 01:04 UTC by Maximiliano Bertacchini
Modified: 2021-05-27 13:28 UTC (History)
4 users (show)

See Also:
Latest Commit: https://invent.kde.org/plasma/ksystemstats/commit/be6a4b3aa80c67aacf61618293b9ec2aacf374d9
Version Fixed In: 5.22

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Description Maximiliano Bertacchini 2021-05-23 01:04:53 UTC 
SUMMARY
ksystemstats always crashes with segmentation fault on start.

STEPS TO REPRODUCE
1. Run ksystemstats.
2. Run plasma-systemmonitor.
3. Run kstatsviewer --list.

OBSERVED RESULT

ksystemstats immediately crashes with sigsegv on start, every time.

plasma-systemmonitor shows all empty charts in its default overview dashboard (but applications and processes do show up).

`kstatsviewer --list` just hangs with no output.


$ ksystemstats
[1] 136376 segmentation fault (core dumped)  ksystemstats

$ sudo dmesg | grep ksystemstats | tail -1
[10634.070037] ksystemstats[136376]: segfault at 5567d285e976 ip 00007f7586c907f1 sp 00007ffc74e328b8 error 4 in libc-2.33.so[7f7586b3b000+16b000]

$ sudo dmesg | grep ksystemstats | wc -l
118

$ gdb ksystemstats
GNU gdb (Ubuntu 10.1-2ubuntu2) 10.1.90.20210411-git
...
Reading symbols from ksystemstats...
Reading symbols from /usr/lib/debug/.build-id/8f/5f3fbc89118665671a2e4c7bad1caba0d97066.debug...
(gdb) r
Starting program: /usr/bin/ksystemstats 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff3923640 (LWP 139026)]
[New Thread 0x7ffff1cff640 (LWP 139027)]
[Detaching after fork from child process 139029]

Thread 1 "ksystemstats" received signal SIGSEGV, Segmentation fault.
__strcmp_avx2 () at ../sysdeps/x86_64/multiarch/strcmp-avx2.S:102
102     ../sysdeps/x86_64/multiarch/strcmp-avx2.S: No such file or directory.
(gdb) bt
#0  __strcmp_avx2 () at ../sysdeps/x86_64/multiarch/strcmp-avx2.S:102
#1  0x00007ffff1d033f9 in sensors_match_chip (chip2=0x5555557ca9a0, chip1=0x55555580d7b0) at lib/access.c:46
#2  sensors_lookup_chip (name=name@entry=0x5555557ca9a0) at lib/access.c:102
#3  0x00007ffff1d0350f in __sensors_get_value (name=0x5555557ca9a0, subfeat_nr=0, depth=depth@entry=0, result=result@entry=0x7fffffffd3e8) at lib/access.c:240
#4  0x00007ffff1d03a9e in sensors_get_value (name=<optimized out>, subfeat_nr=<optimized out>, result=result@entry=0x7fffffffd3e8) at lib/access.c:282
#5  0x00007ffff1d2cdd8 in SensorsFeatureSensor::update (this=0x5555557bf180) at ./plugins/lmsensors/SensorsFeatureSensor.cpp:142
#6  0x00007ffff1d2b97d in LmSensorsPlugin::update (this=<optimized out>) at ./plugins/lmsensors/lmsensors.cpp:65
#7  0x000055555556277d in Daemon::sendFrame (this=0x7fffffffda20) at ./src/daemon.cpp:236
#8  0x00007ffff7beab0e in QtPrivate::QSlotObjectBase::call (a=0x7fffffffd5d0, r=0x7fffffffda20, this=0x5555555939c0) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:398
#9  doActivate<false> (sender=0x555555593930, signal_index=3, argv=argv@entry=0x7fffffffd5d0) at kernel/qobject.cpp:3886
#10 0x00007ffff7be3cb8 in QMetaObject::activate (sender=<optimized out>, m=m@entry=0x7ffff7e4d2a0 <QTimer::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffd5d0) at kernel/qobject.cpp:3946
#11 0x00007ffff7beebfe in QTimer::timeout (this=<optimized out>, _t1=...) at .moc/moc_qtimer.cpp:205
#12 0x00007ffff7be01df in QObject::event (this=0x555555593930, e=0x7fffffffd710) at kernel/qobject.cpp:1336
#13 0x00007ffff7bb31ff in doNotify (event=0x7fffffffd710, receiver=0x555555593930) at kernel/qcoreapplication.cpp:1153
#14 QCoreApplication::notify (event=<optimized out>, receiver=<optimized out>, this=<optimized out>) at kernel/qcoreapplication.cpp:1139
#15 QCoreApplication::notifyInternal2 (receiver=0x555555593930, event=0x7fffffffd710) at kernel/qcoreapplication.cpp:1063
#16 0x00007ffff7c0b8c3 in QTimerInfoList::activateTimers (this=0x555555589380) at kernel/qtimerinfo_unix.cpp:643
#17 0x00007ffff7c0c1bc in timerSourceDispatch (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:183
#18 0x00007ffff6b9f84b in g_main_dispatch (context=0x555555586f20) at ../../../glib/gmain.c:3337
#19 g_main_context_dispatch (context=0x555555586f20) at ../../../glib/gmain.c:4055
#20 0x00007ffff6bf2c68 in g_main_context_iterate.constprop.0 (context=context@entry=0x555555586f20, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../glib/gmain.c:4131
#21 0x00007ffff6b9cf83 in g_main_context_iteration (context=0x555555586f20, may_block=may_block@entry=1) at ../../../glib/gmain.c:4196
#22 0x00007ffff7c0c594 in QEventDispatcherGlib::processEvents (this=0x5555555865a0, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#23 0x00007ffff7bb1b8b in QEventLoop::exec (this=this@entry=0x7fffffffd950, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#24 0x00007ffff7bba024 in QCoreApplication::exec () at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#25 0x000055555555a8b7 in main (argc=<optimized out>, argv=<optimized out>) at ./src/main.cpp:29
(gdb) c
Continuing.
Couldn't get registers: No such process.
Couldn't get registers: No such process.
(gdb) [Thread 0x7ffff1cff640 (LWP 139027) exited]
[Thread 0x7ffff3923640 (LWP 139026) exited]

Program terminated with signal SIGSEGV, Segmentation fault.
The program no longer exists.
q

$ systemctl --user status plasma-ksystemstats.service
● plasma-ksystemstats.service - Track hardware statistics
     Loaded: loaded (/usr/lib/systemd/user/plasma-ksystemstats.service; static)
     Active: failed (Result: core-dump) since Sat 2021-05-22 21:43:38 -03; 2min 1s ago
    Process: 141936 ExecStart=/usr/bin/ksystemstats (code=dumped, signal=SEGV)
   Main PID: 141936 (code=dumped, signal=SEGV)

may 22 21:43:37 max6 systemd[4477]: Starting Track hardware statistics...
may 22 21:43:38 max6 systemd[4477]: Started Track hardware statistics.
may 22 21:43:38 max6 systemd[4477]: plasma-ksystemstats.service: Main process exited, code=dumped, status=11/SEGV
may 22 21:43:38 max6 systemd[4477]: plasma-ksystemstats.service: Failed with result 'core-dump'.
may 22 21:43:38 max6 systemd[4477]: plasma-ksystemstats.service: Start request repeated too quickly.
may 22 21:43:38 max6 systemd[4477]: plasma-ksystemstats.service: Failed with result 'core-dump'.
may 22 21:43:38 max6 systemd[4477]: Failed to start Track hardware statistics.

$ systemctl --user status plasma-plasmashell.service | head -3 
● plasma-plasmashell.service - KDE Plasma Workspace
     Loaded: loaded (/usr/lib/systemd/user/plasma-plasmashell.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2021-05-22 13:11:20 -03; 8h ago


EXPECTED RESULT
No crashes. System monitor and kstatsviewer should show metrics and sensors.

SOFTWARE/OS VERSIONS
Operating System: Ubuntu 21.04
KDE Plasma Version: 5.21.90
KDE Frameworks Version: 5.82.0
Qt Version: 5.15.2
Kernel Version: 5.11.0-17-generic (64-bit)
Graphics Platform: X11
Processors: 12 × Intel® Core™ i7-9750H CPU @ 2.60GHz
Memory: 31,1 GiB of RAM
Graphics Processor: NVIDIA GeForce GTX 1650 with Max-Q Design/PCIe/SSE2

ADDITIONAL INFORMATION
ksysguardd is running, fwiw.
`sensors` working as expected, shows a long list of sensors with their current values.
Comment 1 Marco Martin 2021-05-24 08:38:05 UTC 
seems specifoc to lmsensors
Comment 2 Maximiliano Bertacchini 2021-05-25 03:55:43 UTC 
(In reply to Marco Martin from comment #1)
> seems specifoc to lmsensors

Indeed. Removing the lmsensors plugin from "/usr/lib/x86_64-linux-gnu/qt5/plugins/ksystemstats" unlocks both plasma-systemmonitor and kstatsviewer.
Comment 3 Maximiliano Bertacchini 2021-05-26 04:01:42 UTC 
Managed to debug a locally compiled build and pinpointed the crash to sensors of type SENSORS_FEATURE_IN and SENSORS_FEATURE_CURR. So that if makeSensorsFeatureSensor() returns nullptr on those types, ksystemstats works fine with all the other sensors in my system (2 fans and a lot of temperatures). Alternatively, it also works if SensorsFeatureSensor::update() returns immediately on feature names "in0_input" or "curr1_input".
Comment 4 Maximiliano Bertacchini 2021-05-26 04:02:25 UTC 
Just in case, the output of `sensors` on my laptop:

$ sensors
ucsi_source_psy_USBC000:001-isa-0000
Adapter: ISA adapter
in0:           0.00 V  (min =  +0.00 V, max =  +0.00 V)
curr1:         3.00 A  (max =  +0.00 A)

thinkpad-isa-0000
Adapter: ISA adapter
fan1:        2477 RPM
fan2:        2188 RPM
temp1:        +41.0°C  
temp2:        +41.0°C  
temp3:         +0.0°C  
temp4:         +0.0°C  
temp5:         +0.0°C  
temp6:         +0.0°C  
temp7:         +0.0°C  
temp8:         +0.0°C  
temp9:         +0.0°C  
temp10:        +0.0°C  
temp11:        +1.0°C  
temp12:        +0.0°C  
temp13:       +13.0°C  
temp14:        +0.0°C  
temp15:        +0.0°C  
temp16:        +0.0°C  

coretemp-isa-0000
Adapter: ISA adapter
Package id 0:  +43.0°C  (high = +100.0°C, crit = +100.0°C)
Core 0:        +42.0°C  (high = +100.0°C, crit = +100.0°C)
Core 1:        +41.0°C  (high = +100.0°C, crit = +100.0°C)
Core 2:        +42.0°C  (high = +100.0°C, crit = +100.0°C)
Core 3:        +42.0°C  (high = +100.0°C, crit = +100.0°C)
Core 4:        +41.0°C  (high = +100.0°C, crit = +100.0°C)
Core 5:        +41.0°C  (high = +100.0°C, crit = +100.0°C)

BAT0-acpi-0
Adapter: ACPI interface
in0:          16.14 V  

ucsi_source_psy_USBC000:002-isa-0000
Adapter: ISA adapter
in0:           0.00 V  (min =  +0.00 V, max =  +0.00 V)
curr1:         0.00 A  (max =  +0.00 A)

iwlwifi_1-virtual-0
Adapter: Virtual device
temp1:        +32.0°C  

pch_cannonlake-virtual-0
Adapter: Virtual device
temp1:        +46.0°C  

nvme-pci-0200
Adapter: PCI adapter
Composite:    +44.9°C  (low  =  -5.2°C, high = +79.8°C)
                       (crit = +84.8°C)

acpitz-acpi-0
Adapter: ACPI interface
temp1:        +41.0°C  (crit = +128.0°C)
Comment 5 Nate Graham 2021-05-26 18:48:33 UTC 
Nice work! Would you like to submit a merge request to fix it?
Comment 6 Maximiliano Bertacchini 2021-05-26 21:14:49 UTC 
(In reply to Nate Graham from comment #5)
> Nice work! Would you like to submit a merge request to fix it?

I'd love to, but... I don't yet understand the real issue, let alone how to fix it :) (other than the hack of just ignoring those sensor types). Will keep looking at libsensors internals for now.
Comment 7 David Redondo 2021-05-27 09:59:35 UTC 
Git commit 6be954add10b934f3683bc599849e0fee1da140d by David Redondo.
Committed on 25/05/2021 at 07:43.
Pushed by davidre into branch 'master'.

Init lib sensors centrally in the daemon

Initing muliple times in the same process leads to crashes.

M  +1    -1    autotests/CMakeLists.txt
M  +0    -1    plugins/cpu/linuxcpuplugin.cpp
M  +0    -4    plugins/lmsensors/lmsensors.cpp
M  +6    -0    src/CMakeLists.txt
M  +10   -0    src/daemon.cpp

https://invent.kde.org/plasma/ksystemstats/commit/6be954add10b934f3683bc599849e0fee1da140d
Comment 8 David Redondo 2021-05-27 10:06:10 UTC 
Git commit be6a4b3aa80c67aacf61618293b9ec2aacf374d9 by David Redondo.
Committed on 27/05/2021 at 10:06.
Pushed by davidre into branch 'Plasma/5.22'.

Init lib sensors centrally in the daemon

Initing muliple times in the same process leads to crashes.


(cherry picked from commit 6be954add10b934f3683bc599849e0fee1da140d)

M  +1    -1    autotests/CMakeLists.txt
M  +0    -1    plugins/cpu/linuxcpuplugin.cpp
M  +0    -4    plugins/lmsensors/lmsensors.cpp
M  +6    -0    src/CMakeLists.txt
M  +10   -0    src/daemon.cpp

https://invent.kde.org/plasma/ksystemstats/commit/be6a4b3aa80c67aacf61618293b9ec2aacf374d9