[PATCH 4.5 002/200] block: partition: initialize percpuref before sending out KOBJ_ADD

Greg Kroah-Hartman
2016-05-03T01:25:49Z

From: Ming Lei <ming.lei@canonical.com>

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.

Reported-by: Naveen Kaje <nkaje@codeaurora.org>
Tested-by: Naveen Kaje <nkaje@codeaurora.org>
Fixes: 6c71013ecb7e2(block: partition: convert percpu ref)
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -350,15 +350,20 @@ 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);
@@ -367,6 +372,8 @@ 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);