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libdm: fix segfault with invalid group descriptor

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If a region has a a DMS_GROUP tag in aux_data where the first
region_id in the bitmap is not the same as the containing region,
dmstats will segfault:

  # '2' is never a valid group bitset list for region_id == 0
  # dmsetup message vg_hex/root 0 "@stats_set_aux 0 DMS_GROUP=img:2#"

  # dmsetup message vg_hex/root 0 "@stats_list"
  0: 45383680+16384 16384 dmstats DMS_GROUP=img:2#
  1: 46071808+32768 32768 dmstats -
  2: 47382528+16384 16384 dmstats -

  # dmstats list
  Segmentation fault (core dumped)

The crash will occur in some arbitrary dm_stats_get_* property
method - this happens while processing the 1st region_id in the
bitset, because the region is marked as grouped, but there is
no group bitmap present at dms->groups[2]->regions.

Fix this by detecting a mismatch between the expected region_id
and dm_bit_get_first() for the parsed bitset during
_parse_aux_data_group().
This commit is contained in:
Bryn M. Reeves 2016-12-13 13:56:10 +00:00
parent 138e4336fd
commit 99b6d82e2d
1 changed files with 7 additions and 1 deletions
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8
libdm/libdm-stats.c
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@ -708,8 +708,14 @@ static int _parse_aux_data_group(struct dm_stats *dms,
}
group->group_id = dm_bit_get_first(regions);
group->regions = regions;
if (group->group_id != region->region_id) {
log_error("Found invalid group descriptor in region " FMTu64
" aux_data.", region->region_id);
group->group_id = DM_STATS_GROUP_NOT_PRESENT;
goto bad;
}
group->regions = regions;
group->alias = NULL;
if (strlen(alias)) {
group->alias = dm_strdup(alias);