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

From: Kamal Mostafa
Date: Thu Oct 09 2014 - 17:04:35 EST -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>
[ kamal: backport to 3.13-stable: fixed in cgroup_create() ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
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)

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