[PATCH 3.13 005/163] cgroup: reject cgroup names with '\n'

[Kamal Mostafa]

3.13.11.9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alban Crequy <alban.crequy at collabora.co.uk>

commit 71b1fb5c4473a5b1e601d41b109bdfe001ec82e0 upstream.

/proc/<pid>/cgroup contains one cgroup path on each line. If cgroup names are
allowed to contain "\n", applications cannot parse /proc/<pid>/cgroup safely.

Signed-off-by: Alban Crequy <alban.crequy at collabora.co.uk>
Signed-off-by: Tejun Heo <tj at kernel.org>
[ kamal: backport to 3.13-stable: fixed in cgroup_create() ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 kernel/cgroup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b44dd49..8e5e0a9 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4350,6 +4350,11 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 	struct cgroup_subsys *ss;
 	struct super_block *sb = root->sb;
 
+	/* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
+	 */
+	if (strchr(dentry->d_name.name, '\n'))
+		return -EINVAL;
+
 	/* allocate the cgroup and its ID, 0 is reserved for the root */
 	cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
 	if (!cgrp)
-- 
1.9.1