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| author | Li Zefan <lizefan@huawei.com> | 2013-02-18 14:13:35 +0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-02-18 09:31:35 -0800 |
| commit | f169007b2773f285e098cb84c74aac0154d65ff7 (patch) | |
| tree | 6b295320c25b9fe8c1e4e94fcc35570134ebb8be /kernel/cgroup.c | |
| parent | 810cbee4fad570ff167132d4ecf247d99c48f71d (diff) | |
| download | lwn-f169007b2773f285e098cb84c74aac0154d65ff7.tar.gz lwn-f169007b2773f285e098cb84c74aac0154d65ff7.zip | |
cgroup: fail if monitored file and event_control are in different cgroup
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>
Diffstat (limited to 'kernel/cgroup.c')
| -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 feda81487be4..b5c64327e712 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3856,6 +3856,7 @@ 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; @@ -3911,6 +3912,16 @@ 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; |