diff options
| author | Li Zefan <lizefan@huawei.com> | 2013-02-18 14:13:35 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-10-26 21:06:11 +0100 |
| commit | 31e0470e9906c42edfc4cf00404d4eb3a99dac7e (patch) | |
| tree | f303636e1d66d134748114d94979083e062c4ab6 | |
| parent | 5f7f65dae41a2f2ba134b880d2b9a8bc459ba01b (diff) | |
cgroup: fail if monitored file and event_control are in different cgroup
commit f169007b2773f285e098cb84c74aac0154d65ff7 upstream.
If we pass fd of memory.usage_in_bytes of cgroup A to cgroup.event_control
of cgroup B, then we won't get memory usage notification from A but B!
What's worse, if A and B are in different mount hierarchy, we'll end up
accessing NULL pointer!
Disallow this kind of invalid usage.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | kernel/cgroup.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d2a01fee0d42..2a1ffb7b1915 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3504,6 +3504,7 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, const char *buffer) { struct cgroup_event *event = NULL; + struct cgroup *cgrp_cfile; unsigned int efd, cfd; struct file *efile = NULL; struct file *cfile = NULL; @@ -3559,6 +3560,16 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, goto fail; } + /* + * The file to be monitored must be in the same cgroup as + * cgroup.event_control is. + */ + cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); + if (cgrp_cfile != cgrp) { + ret = -EINVAL; + goto fail; + } + if (!event->cft->register_event || !event->cft->unregister_event) { ret = -EINVAL; goto fail; |