linux-kernel - [PATCH 10/17] cgroup: fix harmless bugs in cgroup_load_subsys() fail path and cgroup_unload

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 12 Nov 2012 19:01:37 -0800
From:	Tejun Heo <tj@...nel.org>
To:	lizefan@...wei.com, containers@...ts.linux-foundation.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	mhocko@...e.cz, glommer@...allels.com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 10/17] cgroup: fix harmless bugs in cgroup_load_subsys() fail path and cgroup_unload_subsys()

* If idr init fails, cgroup_load_subsys() cleared dummytop->subsys[]
  before calilng ->destroy() making CSS inaccessible to the callback,
  and didn't unlink ss->sibling.  As no modular controller uses
  ->use_id, this doesn't cause any actual problems.

* cgroup_unload_subsys() was forgetting to free idr, call
  ->pre_destroy() and clear ->active.  As there currently is no
  modular controller which uses ->use_id, ->pre_destroy() or ->active,
  this doesn't cause any actual problems.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/cgroup.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 76f1a01..c5368c0 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4420,9 +4420,10 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 	if (ss->use_id) {
 		int ret = cgroup_init_idr(ss, css);
 		if (ret) {
-			dummytop->subsys[ss->subsys_id] = NULL;
 			ss->destroy(dummytop);
+			dummytop->subsys[ss->subsys_id] = NULL;
 			subsys[ss->subsys_id] = NULL;
+			list_del_init(&ss->sibling);
 			mutex_unlock(&cgroup_mutex);
 			return ret;
 		}
@@ -4490,7 +4491,19 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
 	 */
 	BUG_ON(ss->root != &rootnode);
 
+	/* ->pre_destroy() should be called outside cgroup_mutex for now */
+	if (ss->pre_destroy)
+		ss->pre_destroy(dummytop);
+
 	mutex_lock(&cgroup_mutex);
+
+	ss->active = 0;
+
+	if (ss->use_id) {
+		idr_remove_all(&ss->idr);
+		idr_destroy(&ss->idr);
+	}
+
 	/* deassign the subsys_id */
 	subsys[ss->subsys_id] = NULL;
 
-- 
1.7.11.7

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/