Bug 2172585

Summary: dmstats create --filemap: error when file name contains whitespace
Product: Red Hat Enterprise Linux 9 Reporter: Bryn M. Reeves <bmr>
Component: lvm2Assignee: LVM Team <lvm-team>
lvm2 sub component: dmsetup QA Contact: cluster-qe <cluster-qe>
Status: NEW --- Docs Contact:
Severity: medium    
Priority: medium CC: agk, heinzm, jbrassow, msnitzer, prajnoha, zkabelac
Version: 9.2Keywords: Triaged
Target Milestone: rc   
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Hardware: All   
OS: Linux   
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Description Bryn M. Reeves 2023-02-22 15:42:58 UTC 
Description of problem:
The dmstats create --filemap operation creates statistics regions that map the extents of a file in a file system and groups them together to aggregate statistics for the file.

This fails when the file name contains whitespace characters:

  # dmstats create --filemap RHEL\ 8.4\ Clone-disk1.vdi
  device-mapper: message ioctl on  (253:0) failed: Invalid argument
  Could not create regions from file /root/RHEL 8.4 Clone/RHEL 8.4 Clone-disk1.vdi.
  free(): double free detected in tcache 2
  Aborted (core dumped)

There are two problems here: the message ioctl fails since whitespace is not supported in the stats region aux_data value:

  dm message   (253:0) [ opencount flush ]  @stats_set_aux 0 DMS_GROUP=RHEL 8.4 Clone-disk1.vdi:0-19#-  [16384] (*1)
  device-mapper: message ioctl on  (253:0) failed: Invalid argument

The embedded space causes stats_set_aux value to be treated as three separate arguments: "DMS_GROUP=RHEL", "8.4", "Clone-disk1.vdi:0-19#-"

The double free is then triggered because the dmstats error path destroys the dm_bitmap used to track group members on error, and this is also freed by the later call to dm_stats_destroy for the stats handle used for the operation.

Renaming the file to use '_' instead of space avoids the error:

  # dmstats create --filemap RHEL_8.4_Clone-disk1.vdi
  RHEL_8.4_Clone-disk1.vdi: Created new group with 4 region(s) as group ID 0.

Version-Release number of selected component (if applicable):
Reproduced on RHEL8, Fedora & current git
device-mapper-1.02.175-9.fc37.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Create a file with space characters in the name
2. Attempt to create stats regions with "dmstats create --filemap ..."


Actual results:
Error setting aux data and double free/abort.

Expected results:
dmstats should be able to map the regions of the file.

Additional info:
The file name is stored in aux_data as a group alias for the group of regions that map the file's extents. One way to avoid the problem would be to escape space characters as "\x20" when passing the alias to the stats_set_aux message.