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Commit e37a06f1 authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

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: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun 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 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, 
	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 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, 
		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;

		}