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ocfs2: fix NULL pointer dereference when traversing o2hb_all_regions 

There may exist NULL pointer dereference in config_item_name() when one
volume (say Volume A) unmounts while another (say Volume B) mounting.

     Volume A                          Volume B

  already Mounted.
  Unmounting, call
  o2hb_heartbeat_group_drop_item()
    -> config_item_put(item)
    set reg(A)->item.ci_name to NULL
    in function config_item_cleanup().

                                    begin mounting, call
                                    o2hb_region_pin() and tranverse all
                                    regions. When reading
                                    reg(A)->item.ci_name, it causes
                                    NULL pointer dereference.

  call o2hb_region_release() and
  del reg(A) from list.

So we should skip accessing regions that is going to release when
tranverse o2hb_all_regions.

Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Signed-off-by: joyce <xuejiufei@huawei.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Sunil Mushran <sunil.mushran@gmail.com>
Cc: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Xue jiufei 2013-07-03 15:01:10 -07:00 committed by Linus Torvalds
parent 44e89cb8e2
commit 4a184b4ff4
1 changed files with 9 additions and 0 deletions
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9
fs/ocfs2/cluster/heartbeat.c
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@ -2389,6 +2389,9 @@ static int o2hb_region_pin(const char *region_uuid)
assert_spin_locked(&o2hb_live_lock);
list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
if (reg->hr_item_dropped)
continue;
uuid = config_item_name(&reg->hr_item);
/* local heartbeat */
@ -2439,6 +2442,9 @@ static void o2hb_region_unpin(const char *region_uuid)
assert_spin_locked(&o2hb_live_lock);
list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
if (reg->hr_item_dropped)
continue;
uuid = config_item_name(&reg->hr_item);
if (region_uuid) {
if (strcmp(region_uuid, uuid))
@ -2654,6 +2660,9 @@ int o2hb_get_all_regions(char *region_uuids, u8 max_regions)
p = region_uuids;
list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
if (reg->hr_item_dropped)
continue;
mlog(0, "Region: %s\n", config_item_name(&reg->hr_item));
if (numregs < max_regions) {
memcpy(p, config_item_name(&reg->hr_item),