[PATCH v2] cgroup: reject cgroup names with '\n'

[Alban Crequy]

/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>
---
v2: Fixed according to comments from Tejun Heo: only reject '\n'

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

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7dc8788..c3d1802 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;
-- 
1.8.5.3

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