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cgroup: fix broken file xattrs

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We should store file xattrs in struct cfent instead of struct cftype,
because cftype is a type while cfent is object instance of cftype.

For example each cgroup has a tasks file, and each tasks file is
associated with a uniq cfent, but all those files share the same
struct cftype.

Alexey Kodanev reported a crash, which can be reproduced:

  # mount -t cgroup -o xattr /sys/fs/cgroup
  # mkdir /sys/fs/cgroup/test
  # setfattr -n trusted.value -v test_value /sys/fs/cgroup/tasks
  # rmdir /sys/fs/cgroup/test
  # umount /sys/fs/cgroup
  oops!

In this case, simple_xattrs_free() will free the same struct simple_xattrs
twice.

tj: Dropped unused local variable @cft from cgroup_diput().

Cc: <stable@vger.kernel.org> # 3.8.x
Reported-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Li Zefan 2013-04-18 23:09:52 -07:00 • committed by Tejun Heo
parent e57d5cf2f8
commit 712317ad97
2 changed files with 6 additions and 8 deletions
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3
include/linux/cgroup.h
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@ -422,9 +422,6 @@ struct cftype {
/* CFTYPE_* flags */
unsigned int flags;
/* file xattrs */
struct simple_xattrs xattrs;
int (*open)(struct inode *inode, struct file *file);
ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
struct file *file,