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Commit 876ede8b authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cgroup: restructure the failure path in cgroup_write_event_control() 



It uses a single label and checks the validity of each pointer. This
is err-prone, and actually we had a bug because one of the check was
insufficient.

Use multi lables as we do in other places.

v2:
- drop initializations of local variables.

Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent e14880f7

kernel/cgroup.c

+18 −21
Original line number Diff line number Diff line
@@ -3934,11 +3934,11 @@ static void cgroup_event_ptable_queue_proc(struct file *file, 
static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,

				      const char *buffer)

{

	struct cgroup_event *event = NULL;

	struct cgroup_event *event;

	struct cgroup *cgrp_cfile;

	unsigned int efd, cfd;

	struct file *efile = NULL;

	struct file *cfile = NULL;

	struct file *efile;

	struct file *cfile;

	char *endp;

	int ret;
@@ -3964,31 +3964,31 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, 
	efile = eventfd_fget(efd);

	if (IS_ERR(efile)) {

		ret = PTR_ERR(efile);

		goto fail;

		goto out_kfree;

	}



	event->eventfd = eventfd_ctx_fileget(efile);

	if (IS_ERR(event->eventfd)) {

		ret = PTR_ERR(event->eventfd);

		goto fail;

		goto out_put_efile;

	}



	cfile = fget(cfd);

	if (!cfile) {

		ret = -EBADF;

		goto fail;

		goto out_put_eventfd;

	}



	/* the process need read permission on control file */

	/* AV: shouldn't we check that it's been opened for read instead? */

	ret = inode_permission(file_inode(cfile), MAY_READ);

	if (ret < 0)

		goto fail;

		goto out_put_cfile;



	event->cft = __file_cft(cfile);

	if (IS_ERR(event->cft)) {

		ret = PTR_ERR(event->cft);

		goto fail;

		goto out_put_cfile;

	}



	/*
@@ -3998,18 +3998,18 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, 
	cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);

	if (cgrp_cfile != cgrp) {

		ret = -EINVAL;

		goto fail;

		goto out_put_cfile;

	}



	if (!event->cft->register_event || !event->cft->unregister_event) {

		ret = -EINVAL;

		goto fail;

		goto out_put_cfile;

	}



	ret = event->cft->register_event(cgrp, event->cft,

			event->eventfd, buffer);

	if (ret)

		goto fail;

		goto out_put_cfile;



	efile->f_op->poll(efile, &event->pt);
@@ -4029,16 +4029,13 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, 


	return 0;



fail:

	if (cfile)

out_put_cfile:

	fput(cfile);



	if (event && event->eventfd && !IS_ERR(event->eventfd))

out_put_eventfd:

	eventfd_ctx_put(event->eventfd);



	if (!IS_ERR_OR_NULL(efile))

out_put_efile:

	fput(efile);



out_kfree:

	kfree(event);



	return ret;