Commit 33d283be authored Nov 19, 2008 by Li Zefan Committed by Linus Torvalds Nov 19, 2008

cgroups: fix a serious bug in cgroupstats



Try this, and you'll get oops immediately:
 # cd Documentation/accounting/
 # gcc -o getdelays getdelays.c
 # mount -t cgroup -o debug xxx /mnt
 # ./getdelays -C /mnt/tasks

Because a normal file's dentry->d_fsdata is a pointer to struct cftype,
not struct cgroup.

After the patch, it returns EINVAL if we try to get cgroupstats
from a normal file.

Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x, 2.6.27.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ea7e743e

kernel/cgroup.c

+5 −2

Original line number	Original line	Diff line number	Diff line
	@@ -2039,10 +2039,13 @@ int cgroupstats_build(struct cgroupstats stats, struct dentry dentry)
	struct cgroup *cgrp;		struct cgroup *cgrp;
	struct cgroup_iter it;		struct cgroup_iter it;
	struct task_struct *tsk;		struct task_struct *tsk;

	/*		/*
	* Validate dentry by checking the superblock operations		* Validate dentry by checking the superblock operations,
			* and make sure it's a directory.
	*/		*/
	if (dentry->d_sb->s_op != &cgroup_ops)		if (dentry->d_sb->s_op != &cgroup_ops \|\|
			!S_ISDIR(dentry->d_inode->i_mode))
	goto err;		goto err;

	ret = 0;		ret = 0;

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