diff options
author | Chen Gang <gang.chen@asianux.com> | 2013-06-12 14:05:07 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-06-12 16:29:46 -0700 |
commit | 736f3203a06eafd0944103775a98584082744c6b (patch) | |
tree | e0d42a615dd56a7e8ae301e3ccbb8a074b33273e /kernel | |
parent | 30dad30922ccc733cfdbfe232090cf674dc374dc (diff) |
kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules()
audit_add_tree_rule() must set 'rule->tree = NULL;' firstly, to protect
the rule itself freed in kill_rules().
The reason is when it is killed, the 'rule' itself may have already
released, we should not access it. one example: we add a rule to an
inode, just at the same time the other task is deleting this inode.
The work flow for adding a rule:
audit_receive() -> (need audit_cmd_mutex lock)
audit_receive_skb() ->
audit_receive_msg() ->
audit_receive_filter() ->
audit_add_rule() ->
audit_add_tree_rule() -> (need audit_filter_mutex lock)
...
unlock audit_filter_mutex
get_tree()
...
iterate_mounts() -> (iterate all related inodes)
tag_mount() ->
tag_trunk() ->
create_trunk() -> (assume it is 1st rule)
fsnotify_add_mark() ->
fsnotify_add_inode_mark() -> (add mark to inode->i_fsnotify_marks)
...
get_tree(); (each inode will get one)
...
lock audit_filter_mutex
The work flow for deleting an inode:
__destroy_inode() ->
fsnotify_inode_delete() ->
__fsnotify_inode_delete() ->
fsnotify_clear_marks_by_inode() -> (get mark from inode->i_fsnotify_marks)
fsnotify_destroy_mark() ->
fsnotify_destroy_mark_locked() ->
audit_tree_freeing_mark() ->
evict_chunk() ->
...
tree->goner = 1
...
kill_rules() -> (assume current->audit_context == NULL)
call_rcu() -> (rule->tree != NULL)
audit_free_rule_rcu() ->
audit_free_rule()
...
audit_schedule_prune() -> (assume current->audit_context == NULL)
kthread_run() -> (need audit_cmd_mutex and audit_filter_mutex lock)
prune_one() -> (delete it from prue_list)
put_tree(); (match the original get_tree above)
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/audit_tree.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index a291aa23fb3..43c307dc945 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -658,6 +658,7 @@ int audit_add_tree_rule(struct audit_krule *rule) struct vfsmount *mnt; int err; + rule->tree = NULL; list_for_each_entry(tree, &tree_list, list) { if (!strcmp(seed->pathname, tree->pathname)) { put_tree(seed); |