4.19-stable review patch. If anyone has any objections, please let me know.
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From: Xiu Jianfeng xiujianfeng@huawei.com
[ Upstream commit 3cc4e13bb1617f6a13e5e6882465984148743cf4 ]
cgroup.max.depth is the maximum allowed descent depth below the current cgroup. If the actual descent depth is equal or larger, an attempt to create a new child cgroup will fail. However due to the cgroup->max_depth is of int type and having the default value INT_MAX, the condition 'level > cgroup->max_depth' will never be satisfied, and it will cause an overflow of the level after it reaches to INT_MAX.
Fix it by starting the level from 0 and using '>=' instead.
It's worth mentioning that this issue is unlikely to occur in reality, as it's impossible to have a depth of INT_MAX hierarchy, but should be be avoided logically.
Fixes: 1a926e0bbab8 ("cgroup: implement hierarchy limits") Signed-off-by: Xiu Jianfeng xiujianfeng@huawei.com Reviewed-by: Michal Koutný mkoutny@suse.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cgroup/cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 30c0588067029..4ab74d06be194 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5104,7 +5104,7 @@ static bool cgroup_check_hierarchy_limits(struct cgroup *parent) { struct cgroup *cgroup; int ret = false; - int level = 1; + int level = 0;
lockdep_assert_held(&cgroup_mutex);
@@ -5112,7 +5112,7 @@ static bool cgroup_check_hierarchy_limits(struct cgroup *parent) if (cgroup->nr_descendants >= cgroup->max_descendants) goto fail;
- if (level > cgroup->max_depth) + if (level >= cgroup->max_depth) goto fail;
level++;