From: Alexander Kuznetsov wwfq@yandex-team.ru
commit b7e24eb1caa5f8da20d405d262dba67943aedc42 upstream.
cgroup_mkdir() have restriction on newline usage in names: $ mkdir $'/sys/fs/cgroup/cpu/test\ntest2' mkdir: cannot create directory '/sys/fs/cgroup/cpu/test\ntest2': Invalid argument
But in cgroup1_rename() such check is missed. This allows us to make /proc/<pid>/cgroup unparsable: $ mkdir /sys/fs/cgroup/cpu/test $ mv /sys/fs/cgroup/cpu/test $'/sys/fs/cgroup/cpu/test\ntest2' $ echo $$ > $'/sys/fs/cgroup/cpu/test\ntest2' $ cat /proc/self/cgroup 11:pids:/ 10:freezer:/ 9:hugetlb:/ 8:cpuset:/ 7:blkio:/user.slice 6:memory:/user.slice 5:net_cls,net_prio:/ 4:perf_event:/ 3:devices:/user.slice 2:cpu,cpuacct:/test test2 1:name=systemd:/ 0::/
Signed-off-by: Alexander Kuznetsov wwfq@yandex-team.ru Reported-by: Andrey Krasichkov buglloc@yandex-team.ru Acked-by: Dmitry Yakunin zeil@yandex-team.ru Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/cgroup.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3310,6 +3310,10 @@ static int cgroup_rename(struct kernfs_n struct cgroup *cgrp = kn->priv; int ret;
+ /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */ + if (strchr(new_name_str, '\n')) + return -EINVAL; + if (kernfs_type(kn) != KERNFS_DIR) return -ENOTDIR; if (kn->parent != new_parent)