cgroup: reject cgroup names with '\n'

/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@collabora.co.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

1 files changed, 5 insertions, 0 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7dc8788cfd52..c3d1802a9b30 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4543,6 +4543,11 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
         struct cftype *base_files;
         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;