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Description of problem:
Running the `lvs` command with many fields including -o cache_policy and passing a significant number of VGs with cached LVs to the command results in corrupted output in the 'Cache Policy' column.
Version-Release number of selected component (if applicable):
# rpm -qa |grep lvm2
lvm2-2.02.130-5.el7_2.5.x86_64
lvm2-libs-2.02.130-5.el7_2.5.x86_64
How reproducible:
Consistently
Steps to Reproduce:
1.Create more than 5 cached LVs
2.Run `lvs -a -o name,vg_name,size,pool_lv,devices,cachemode,cache_policy,cache_settings,chunksize vg{a..f}`
Actual results:
Most fields in the 'Cache Policy' column show corrupted characters.
Expected results:
All 'Cache Policy' fields should correctly show the current policy.
Additional info:
Appears to be some kind of buffer overflow. The persistence of the issue is dependent on the number of fields displayed in the `lvs` output. For me with the command above,listing the output from 5 VGs works, but 6 VGs shows the corrupted characters. If I reduce the number of fields, 6 VGs may work and 7 may fail.
Comment 2Jonathan Earl Brassow
2017-03-08 23:27:27 UTC
Could you please show the output? Also, RHEL7.3 is out, could you test with that please?
I think this is already fixed with
https://sourceware.org/git/?p=lvm2.git;a=commit;h=a83d611a86e6da31f255d5d87adf14cb3d62a05a
The fix appeared in lvm2 v2.02.140. It was a regression since lvm2 v2.02.126.
I checked the lvm2-2.02.130-5.el7_2.5.x86_64 with valgrind and I hit the problems for which this patch was aimed for - that patch is not included in 7.2.z yet (not sure if we want to backport that or not).
It should fixed in 7.3 and higher releases.
With valgrind, this problem is exposed as:
#valgrind lvs -a -o name,vg_name,size,pool_lv,devices,cachemode,cache_policy,cache_settings,chunksize
...
==10689== Invalid read of size 1
==10689== at 0x4C30B5B: strnlen (vg_replace_strmem.c:421)
==10689== by 0x5B96AA4: vfprintf (vfprintf.c:1637)
==10689== by 0x5BC0488: vsnprintf (vsnprintf.c:114)
==10689== by 0x54CFB23: dm_snprintf (libdm-string.c:129)
==10689== by 0x54C5E8C: _output_field (libdm-report.c:4244)
==10689== by 0x54C684E: _output_as_columns (libdm-report.c:4390)
==10689== by 0x54C6B3A: dm_report_output (libdm-report.c:4434)
==10689== by 0x15CE0C: _report (reporter.c:934)
==10689== by 0x15CF0A: lvs (reporter.c:953)
==10689== by 0x14E560: lvm_run_command (lvmcmdline.c:1655)
==10689== by 0x14FB49: lvm2_main (lvmcmdline.c:2121)
==10689== by 0x172BEF: main (lvm.c:22)
Description of problem: Running the `lvs` command with many fields including -o cache_policy and passing a significant number of VGs with cached LVs to the command results in corrupted output in the 'Cache Policy' column. Version-Release number of selected component (if applicable): # rpm -qa |grep lvm2 lvm2-2.02.130-5.el7_2.5.x86_64 lvm2-libs-2.02.130-5.el7_2.5.x86_64 How reproducible: Consistently Steps to Reproduce: 1.Create more than 5 cached LVs 2.Run `lvs -a -o name,vg_name,size,pool_lv,devices,cachemode,cache_policy,cache_settings,chunksize vg{a..f}` Actual results: Most fields in the 'Cache Policy' column show corrupted characters. Expected results: All 'Cache Policy' fields should correctly show the current policy. Additional info: Appears to be some kind of buffer overflow. The persistence of the issue is dependent on the number of fields displayed in the `lvs` output. For me with the command above,listing the output from 5 VGs works, but 6 VGs shows the corrupted characters. If I reduce the number of fields, 6 VGs may work and 7 may fail.