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Bug 2016204 - traceback if there is non-utf8 character in the /proc/PID/cmdline
Summary: traceback if there is non-utf8 character in the /proc/PID/cmdline
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: python-linux-procfs
Version: 8.6
Hardware: x86_64
OS: Linux
high
high
Target Milestone: rc
: ---
Assignee: John Kacur
QA Contact: Qiao Zhao
URL:
Whiteboard:
: 2028367 (view as bug list)
Depends On:
Blocks: 2022530 2031717
TreeView+ depends on / blocked
 
Reported: 2021-10-20 23:08 UTC by Jaroslav Škarvada
Modified: 2022-05-10 16:43 UTC (History)
5 users (show)

Fixed In Version: python-linux-procfs-0.6.3-4.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 2022530 2031717 (view as bug list)
Environment:
Last Closed: 2022-05-10 15:24:48 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
Helper script (74 bytes, application/x-shellscript)
2021-10-20 23:09 UTC, Jaroslav Škarvada 		no flags Details
Main reproducer to run (58 bytes, application/x-shellscript)
2021-10-20 23:10 UTC, Jaroslav Škarvada 		no flags Details
Python script called by the main reproducer (113 bytes, text/x-python3)
2021-10-20 23:12 UTC, Jaroslav Škarvada 		no flags Details
Helper to reproduce the problem with the python3-linux-procfs-0.6.3-3 (88 bytes, application/x-shellscript)
2021-12-07 10:27 UTC, Jaroslav Škarvada 		no flags Details
View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-100429 0 None None None 2021-10-20 23:09:12 UTC
Red Hat Product Errata RHBA-2022:2064 0 None None None 2022-05-10 15:25:00 UTC

Description Jaroslav Škarvada 2021-10-20 23:08:14 UTC 
Description of problem:
Processes can set arbitrary characters to their cmdline and procfs will traceback in case there is non-utf8 character in the cmdline.

Version-Release number of selected component (if applicable):
python3-linux-procfs-0.6.3-1.el8

How reproducible:
Always

Steps to Reproduce:
1. Copy three attached files (repr, test.py, helper) to the target system
2. ./repr

Actual results:
raceback (most recent call last):
  File "./test.py", line 6, in <module>
    cmdline = procfs.process_cmdline(procfs.process(int(sys.argv[1])))
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 43, in process_cmdline
    if pid_info["cmdline"]:
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 343, in __getitem__
    self.load_cmdline()
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 361, in load_cmdline
    self.cmdline = f.readline().strip().split('\0')[:-1]
  File "/usr/lib64/python3.6/codecs.py", line 321, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc8 in position 0: invalid continuation byte

Expected results:
No traceback

Additional info:
We use procfs in TuneD and we are seeing this tracebacks in customer reports. The procfs should cope with arbitrary characters in the cmdline and not traceback, e.g. instead of utf strings it could handle it as byte array.
Comment 1 Jaroslav Škarvada 2021-10-20 23:09:55 UTC 
Created attachment 1835346 [details]
Helper script
Comment 2 Jaroslav Škarvada 2021-10-20 23:10:41 UTC 
Created attachment 1835347 [details]
Main reproducer to run
Comment 3 Jaroslav Škarvada 2021-10-20 23:12:04 UTC 
Created attachment 1835348 [details]
Python script called by the main reproducer
Comment 4 John Kacur 2021-11-05 15:53:14 UTC 
I'm not able to reproduce the problem with those scripts, is there something missing?
Comment 7 John Kacur 2021-11-05 20:03:42 UTC 
One potential solution is this, but I want to play with it a bit before I decide.

diff --git a/procfs/procfs.py b/procfs/procfs.py
index 3b7474cccb01..a297058d98dd 100755
--- a/procfs/procfs.py
+++ b/procfs/procfs.py
@@ -357,8 +357,9 @@ class process:
         return hasattr(self, attr)
 
     def load_cmdline(self):
-        f = open("/proc/%d/cmdline" % self.pid)
-        self.cmdline = f.readline().strip().split('\0')[:-1]
+        f = open("/proc/%d/cmdline" % self.pid, mode='rb')
+        cmdline = f.readline().decode(encoding='unicode_escape')
+        self.cmdline = cmdline.strip().split('\0')[:-1]
         f.close()
 
     def load_threads(self):
Comment 13 Jaroslav Škarvada 2021-12-03 10:05:16 UTC 
*** Bug 2028367 has been marked as a duplicate of this bug. ***
Comment 14 Jaroslav Škarvada 2021-12-03 10:13:01 UTC 
There is another bug 2028367. I am not sure whether it was reproduced with the fixed version of the python-linux-procfs (I asked reporter to specify the python-linux-procfs version he used), but the traceback is the following now:

2021-12-01 11:42:58,660 ERROR    tuned.units.manager: Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/tuned/units/manager.py", line 119, in _try_call
    return f(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/instance/instance.py", line 87, in unapply_tuning
    self._plugin.instance_unapply_tuning(self, full_rollback)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/base.py", line 312, in instance_unapply_tuning
    self._instance_unapply_static(instance, full_rollback)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 720, in _instance_unapply_static
    self._restore_ps_affinity()
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 676, in _restore_ps_affinity
    ps = self.get_processes()
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 291, in get_processes
    cmd = self._get_cmdline(proc)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 279, in _get_cmdline
    cmdline = procfs.process_cmdline(process)
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 43, in process_cmdline
    if pid_info["cmdline"]:
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 356, in __getitem__
    self.load_cmdline()
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 374, in load_cmdline
    cmdline = f.readline().decode(encoding='unicode_escape')
UnicodeDecodeError: 'unicodeescape' codec can't decode bytes in position 22-23: truncated \uXXXX escape

I.e. there is now:
cmdline = f.readline().decode(encoding='unicode_escape')
you mentioned in the comment 7.
Comment 15 Jaroslav Škarvada 2021-12-03 10:17:54 UTC 
(In reply to Jaroslav Škarvada from comment #14)
> There is another bug 2028367. I am not sure whether it was reproduced with
> the fixed version of the python-linux-procfs (I asked reporter to specify
> the python-linux-procfs version he used), but the traceback is the following
> now:
> 
> 2021-12-01 11:42:58,660 ERROR    tuned.units.manager: Traceback (most recent
> call last):
>   File "/usr/lib/python3.6/site-packages/tuned/units/manager.py", line 119,
> in _try_call
>     return f(*args, **kwargs)
>   File
> "/usr/lib/python3.6/site-packages/tuned/plugins/instance/instance.py", line
> 87, in unapply_tuning
>     self._plugin.instance_unapply_tuning(self, full_rollback)
>   File "/usr/lib/python3.6/site-packages/tuned/plugins/base.py", line 312,
> in instance_unapply_tuning
>     self._instance_unapply_static(instance, full_rollback)
>   File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py",
> line 720, in _instance_unapply_static
>     self._restore_ps_affinity()
>   File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py",
> line 676, in _restore_ps_affinity
>     ps = self.get_processes()
>   File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py",
> line 291, in get_processes
>     cmd = self._get_cmdline(proc)
>   File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py",
> line 279, in _get_cmdline
>     cmdline = procfs.process_cmdline(process)
>   File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 43, in
> process_cmdline
>     if pid_info["cmdline"]:
>   File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 356, in
> __getitem__
>     self.load_cmdline()
>   File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 374, in
> load_cmdline
>     cmdline = f.readline().decode(encoding='unicode_escape')
> UnicodeDecodeError: 'unicodeescape' codec can't decode bytes in position
> 22-23: truncated \uXXXX escape
> 
> I.e. there is now:
> cmdline = f.readline().decode(encoding='unicode_escape')
> you mentioned in the comment 7.

It was reproduced with the python3-linux-procfs-0.6.3-3.el8, so your fix is probably not OK, moving to assigned.
Comment 19 Jaroslav Škarvada 2021-12-07 10:27:01 UTC 
Created attachment 1845048 [details]
Helper to reproduce the problem with the python3-linux-procfs-0.6.3-3
Comment 21 mhou 2021-12-08 03:31:50 UTC 
This bug affects RT kenrel test on CTC1. I consider escalating this bug priority.
Comment 23 mhou 2021-12-09 02:48:34 UTC 
Hello folks

I find this bug block tuning on rhel 8.6. Here is my test environment

python3-linux-procfs-0.6.3-3.el8.noarch
# uname -r
4.18.0-353.rt7.138.el8.x86_64

# cat > /etc/tuned/realtime-virtual-host-variables.conf  <<-EOF
isolated_cores=2,4,6,8,10,12,14,16,18,20,22,24,26,28,30
isolate_managed_irq=Y
EOF

# cat /etc/tuned/realtime-virtual-host-variables.conf 
isolated_cores=2,4,6,8,10,12,14,16,18,20,22,24,26,28,30
isolate_managed_irq=Y

tuned failed log:
2021-12-08 07:51:04,487 ERROR    tuned.units.manager: BUG: Unhandled exception in stop_tuning: 'unicodeescape' codec can't decode bytes in position 22-23: truncated \uXXXX
escape
2021-12-08 07:51:04,487 ERROR    tuned.units.manager: Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/tuned/units/manager.py", line 119, in _try_call
    return f(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/instance/instance.py", line 87, in unapply_tuning
    self._plugin.instance_unapply_tuning(self, full_rollback)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/base.py", line 312, in instance_unapply_tuning
    self._instance_unapply_static(instance, full_rollback)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 720, in _instance_unapply_static
    self._restore_ps_affinity()
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 676, in _restore_ps_affinity
    ps = self.get_processes()
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 291, in get_processes
    cmd = self._get_cmdline(proc)
  File "/usr/lib/python3.6/site-packages/tuned/plugins/plugin_scheduler.py", line 279, in _get_cmdline
    cmdline = procfs.process_cmdline(process)
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 43, in process_cmdline
    if pid_info["cmdline"]:
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 356, in __getitem__
    self.load_cmdline()
  File "/usr/lib/python3.6/site-packages/procfs/procfs.py", line 374, in load_cmdline
    cmdline = f.readline().decode(encoding='unicode_escape')
UnicodeDecodeError: 'unicodeescape' codec can't decode bytes in position 22-23: truncated \uXXXX escape
Comment 24 mhou 2021-12-09 03:06:01 UTC 
another tool script also have this issue. I have uploaded dpdk_nic_bind.py on attachment.

./dpdk_nic_bind.py -u 0000:5e:00.0
Traceback (most recent call last):
  File "./dpdk_nic_bind.py", line 1048, in <module>
    main()
  File "./dpdk_nic_bind.py", line 1042, in main
    do_arg_actions()
  File "./dpdk_nic_bind.py", line 1025, in do_arg_actions
    unbind_all(args, force_flag)
  File "./dpdk_nic_bind.py", line 713, in unbind_all
    unbind_one(d, force)
  File "./dpdk_nic_bind.py", line 599, in unbind_one
    (dev[b"Slot"], dev[b"Device_str"], dev[b"Interface"]))
KeyError: b'Slot'

# dpdk-devbind.py --status

Network devices using kernel driver
===================================
0000:18:00.0 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno1 drv=tg3 unused=igb_uio,vfio-pci *Active*
0000:18:00.1 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno2 drv=tg3 unused=igb_uio,vfio-pci 
0000:19:00.0 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno3 drv=tg3 unused=igb_uio,vfio-pci 
0000:19:00.1 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno4 drv=tg3 unused=igb_uio,vfio-pci 
0000:3b:00.0 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens1f0 drv=i40e unused=igb_uio,vfio-pci 
0000:3b:00.1 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens1f1 drv=i40e unused=igb_uio,vfio-pci 
0000:5e:00.0 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens3f0 drv=i40e unused=igb_uio,vfio-pci 
0000:5e:00.1 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens3f1 drv=i40e unused=igb_uio,vfio-pci
Comment 26 John Kacur 2021-12-09 15:31:47 UTC 
(In reply to mhou from comment #24)
> another tool script also have this issue. I have uploaded dpdk_nic_bind.py
> on attachment.
> 
> ./dpdk_nic_bind.py -u 0000:5e:00.0
> Traceback (most recent call last):
>   File "./dpdk_nic_bind.py", line 1048, in <module>
>     main()
>   File "./dpdk_nic_bind.py", line 1042, in main
>     do_arg_actions()
>   File "./dpdk_nic_bind.py", line 1025, in do_arg_actions
>     unbind_all(args, force_flag)
>   File "./dpdk_nic_bind.py", line 713, in unbind_all
>     unbind_one(d, force)
>   File "./dpdk_nic_bind.py", line 599, in unbind_one
>     (dev[b"Slot"], dev[b"Device_str"], dev[b"Interface"]))
> KeyError: b'Slot'
> 
> # dpdk-devbind.py --status
> 
> Network devices using kernel driver
> ===================================
> 0000:18:00.0 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno1 drv=tg3
> unused=igb_uio,vfio-pci *Active*
> 0000:18:00.1 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno2 drv=tg3
> unused=igb_uio,vfio-pci 
> 0000:19:00.0 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno3 drv=tg3
> unused=igb_uio,vfio-pci 
> 0000:19:00.1 'NetXtreme BCM5720 Gigabit Ethernet PCIe 165f' if=eno4 drv=tg3
> unused=igb_uio,vfio-pci 
> 0000:3b:00.0 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens1f0
> drv=i40e unused=igb_uio,vfio-pci 
> 0000:3b:00.1 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens1f1
> drv=i40e unused=igb_uio,vfio-pci 
> 0000:5e:00.0 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens3f0
> drv=i40e unused=igb_uio,vfio-pci 
> 0000:5e:00.1 'Ethernet Controller XXV710 for 25GbE SFP28 158b' if=ens3f1
> drv=i40e unused=igb_uio,vfio-pci

Not exactly a standalone script.
In any case the original "fix" actually increased the problem, but the original problem is hard to trigger.
Comment 27 John Kacur 2021-12-09 15:33:52 UTC 
I have a patch that will "fix" this.

Commit 7570fc0d6082 meant to solve the UnicodeDecodeError

Instead it actually increased the problem by reading lines as bytes
and decoding them.

The original problem is hard to trigger and doesn't trigger consistently
with reproducers. In addition there seems to be a difference in how this
is handled between python-3.6 to python-3.9

For now, we should return the code to reading as utf-8 (the default)
since that handles more cases than the current code.

We can catch the UnicodeDecodeError and ignore it for now. It is not
ideal because we are not handling some pids that trigger the error.

This patch also includes a fix for a FileNotFoundError which can occur if
a pid exits and disappears before we try to read it in the /proc file
system.
Comment 32 Jaroslav Škarvada 2021-12-13 10:18:22 UTC 
We are seeing this traceback also on the RHEL-9 now (bug 2031645), cloning to RHEL-9.
Comment 40 errata-xmlrpc 2022-05-10 15:24:48 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (python-linux-procfs bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:2064
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