[PATCH 3.16 206/357] cgroup: reject cgroup names with \n

[Greg Kroah-Hartman]

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

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

From: Alban Crequy <alban.crequy@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/cgroup.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4393,6 +4393,11 @@ static int cgroup_mkdir(struct kernfs_no
 	struct kernfs_node *kn;
 	int ssid, ret;
 
+	/* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
+	 */
+	if (strchr(name, '\n'))
+		return -EINVAL;
+
 	parent = cgroup_kn_lock_live(parent_kn);
 	if (!parent)
 		return -ENODEV;


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