From 4a184b4ff424e544359f081087723fc36efe603e Mon Sep 17 00:00:00 2001 From: Xue jiufei Date: Wed, 3 Jul 2013 15:01:10 -0700 Subject: [PATCH] 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 Signed-off-by: joyce Acked-by: Joel Becker Cc: Mark Fasheh Cc: Sunil Mushran Cc: Jie Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/cluster/heartbeat.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c index 956d79d1fdde..5c1c864e81cc 100644 --- a/fs/ocfs2/cluster/heartbeat.c +++ b/fs/ocfs2/cluster/heartbeat.c @@ -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(®->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(®->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(®->hr_item)); if (numregs < max_regions) { memcpy(p, config_item_name(®->hr_item),