Patch "block: partition: initialize percpuref before sending out KOBJ_ADD" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

block: partition: initialize percpuref before sending out KOBJ_ADD

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
block-partition-initialize-percpuref-before-sending-out-kobj_add.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ming Lei <[email protected]>
Date: Wed, 30 Mar 2016 08:46:31 +0800
Subject: block: partition: initialize percpuref before sending out KOBJ_ADD

From: Ming Lei <[email protected]>

commit b30a337ca27c4f40439e4bfb290cba5f88d73bb7 upstream.

The initialization of partition's percpu_ref should have been done before sending out KOBJ_ADD uevent, which may cause userspace to read partition table. So the uninitialized percpu_ref may be accessed in data path.

This patch fixes this issue reported by Naveen.

---
 block/partition-generic.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

@@ -349,15 +349,20 @@ struct hd_struct *add_partition(struct g
 			goto out_del;
 	}
 
+	err = hd_ref_init(p);
+	if (err) {
+		if (flags & ADDPART_FLAG_WHOLEDISK)
+			goto out_remove_file;
+		goto out_del;
+	}
+
 	/* everything is up and running, commence */
 	rcu_assign_pointer(ptbl->part[partno], p);
 
 	/* suppress uevent if the disk suppresses it */
 	if (!dev_get_uevent_suppress(ddev))
 		kobject_uevent(&pdev->kobj, KOBJ_ADD);
-
-	if (!hd_ref_init(p))
-		return p;
+	return p;
 
 out_free_info:
 	free_part_info(p);

@@ -366,6 +371,8 @@ out_free_stats:
 out_free:
 	kfree(p);
 	return ERR_PTR(err);
+out_remove_file:
+	device_remove_file(pdev, &dev_attr_whole_disk);
 out_del:
 	kobject_put(p->holder_dir);
 	device_del(pdev);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/block-partition-initialize-percpuref-before-sending-out-kobj_add.patch queue-4.4/block-loop-fix-filesystem-corruption-in-case-of-aio-dio.patch