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authorLi Zefan <lizefan@huawei.com>2013-05-14 19:44:20 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-06-07 12:53:05 -0700
commit24622f8bb1d75e005f6cd1ccaea82b72e31b6d6c (patch)
tree39dc535b002650b3c959e15a219cc6c494d44d98
parent52f36be0f4e2fafa5dd85fbd6508bbfba314fd58 (diff)
cgroup: initialize xattr before calling d_instantiate()
commit d6cbf35dac8a3dadb9103379820c96d7c85df3d9 upstream. cgroup_create_file() calls d_instantiate(), which may decide to look at the xattrs on the file. Smack always does this and SELinux can be configured to do so. But cgroup_add_file() didn't initialize xattrs before calling cgroup_create_file(), which finally leads to dereferencing NULL dentry->d_fsdata. This bug has been there since cgroup xattr was introduced. Reported-by: Ivan Bulatovic <combuster@archlinux.us> Reported-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/cgroup.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ba1f9776dd10..95e08e30c176 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2747,13 +2747,14 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
goto out;
}
+ cfe->type = (void *)cft;
+ cfe->dentry = dentry;
+ dentry->d_fsdata = cfe;
+ simple_xattrs_init(&cfe->xattrs);
+
mode = cgroup_file_mode(cft);
error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);
if (!error) {
- cfe->type = (void *)cft;
- cfe->dentry = dentry;
- dentry->d_fsdata = cfe;
- simple_xattrs_init(&cfe->xattrs);
list_add_tail(&cfe->node, &parent->files);
cfe = NULL;
}