Commit e37a06f1 authored Apr 17, 2014 by Li Zefan Committed by Tejun Heo Apr 17, 2014

cgroup: fix the retry path of cgroup_mount()



If we hit the retry path, we'll call parse_cgroupfs_options() again,
but the string we pass to it has been modified by the previous call
to this function.

This bug can be observed by:

  # mount -t cgroup -o name=foo,cpuset xxx /mnt && umount /mnt && \
    mount -t cgroup -o name=foo,cpuset xxx /mnt
  mount: wrong fs type, bad option, bad superblock on xxx,
         missing codepage or helper program, or other error
  ...

The second mount passed "name=foo,cpuset" to the parser, and then it
hit the retry path and call the parser again, but this time the string
passed to the parser is "name=foo".

To fix this, we avoid calling parse_cgroupfs_options() again in this
case.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent c9eaa447

kernel/cgroup.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -1495,7 +1495,7 @@ static struct dentry cgroup_mount(struct file_system_type fs_type,
		*/
		if (!use_task_css_set_links)
		cgroup_enable_task_cg_lists();
		retry:

		mutex_lock(&cgroup_tree_mutex);
		mutex_lock(&cgroup_mutex);

		@@ -1503,7 +1503,7 @@ retry:
		ret = parse_cgroupfs_options(data, &opts);
		if (ret)
		goto out_unlock;

		retry:
		/* look for a matching existing root */
		if (!opts.subsys_mask && !opts.none && !opts.name) {
		cgrp_dfl_root_visible = true;
		@@ -1562,9 +1562,9 @@ retry:
		if (!atomic_inc_not_zero(&root->cgrp.refcnt)) {
		mutex_unlock(&cgroup_mutex);
		mutex_unlock(&cgroup_tree_mutex);
		kfree(opts.release_agent);
		kfree(opts.name);
		msleep(10);
		mutex_lock(&cgroup_tree_mutex);
		mutex_lock(&cgroup_mutex);
		goto retry;
		}

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