sysfs: Fix internal_create_group() for named group updates (c855cf27) · Commits · 戴 / test

There are a couple of problems with named group updates in the code today: * sysfs_update_group() will always fail for a named group, because internal_create_group() will try to create a new sysfs directory unconditionally, which will ofcourse fail with -EEXIST. * We can leak the kernfs_node for grp->name if some one tries to: - rename a group (change grp->name), or - update a named group, to an unnamed group It appears that the whole purpose of sysfs_update_group() was to allow changing the permissions or visibility of attributes and not the names. So make it clear in the comments, and allow it to update an existing named group. Signed-off-by:

Rajat Jain <rajatja@google.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/sysfs/group.c

+22 −7

Original line number	Diff line number	Diff line
		@@ -119,13 +119,23 @@ static int internal_create_group(struct kobject *kobj, int update,
		return -EINVAL;
		}
		if (grp->name) {
		if (update) {
		kn = kernfs_find_and_get(kobj->sd, grp->name);
		if (!kn) {
		pr_warn("Can't update unknown attr grp name: %s/%s\n",
		kobj->name, grp->name);
		return -EINVAL;
		}
		} else {
		kn = kernfs_create_dir(kobj->sd, grp->name,
		S_IRWXU \| S_IRUGO \| S_IXUGO, kobj);
		S_IRWXU \| S_IRUGO \| S_IXUGO,
		kobj);
		if (IS_ERR(kn)) {
		if (PTR_ERR(kn) == -EEXIST)
		sysfs_warn_dup(kobj->sd, grp->name);
		return PTR_ERR(kn);
		}
		}
		} else
		kn = kobj->sd;
		kernfs_get(kn);
		@@ -135,6 +145,10 @@ static int internal_create_group(struct kobject *kobj, int update,
		kernfs_remove(kn);
		}
		kernfs_put(kn);

		if (grp->name && update)
		kernfs_put(kn);

		return error;
		}

		@@ -199,7 +213,8 @@ EXPORT_SYMBOL_GPL(sysfs_create_groups);
		* of the attribute files being created already exist. Furthermore,
		* if the visibility of the files has changed through the is_visible()
		* callback, it will update the permissions and add or remove the
		* relevant files.
		* relevant files. Changing a group's name (subdirectory name under
		* kobj's directory in sysfs) is not allowed.
		*
		* The primary use for this function is to call it after making a change
		* that affects group visibility.

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