Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 025/100] cgroup: fail if monitored file and event_control are in different cgroup | Date | Fri, 11 Oct 2013 11:40:55 +0100 |
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3.5.7.23 -stable review patch. If anyone has any objections, please let me know.
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From: Li Zefan <lizefan@huawei.com>
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> Cc: Weng Meiling <wengmeiling.weng@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- kernel/cgroup.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3b3fa5b..7720f52 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3712,6 +3712,7 @@ 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; @@ -3767,6 +3768,16 @@ 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; -- 1.8.3.2
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