md: fix use after free when removing rdev via sysfs

rdev->mddev is no longer valid upon return from entry->store() when the
'remove' command is given.

Cc: <stable@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index bb3e4b1..11457a2 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2097,7 +2097,7 @@ rdev_attr_store(struct kobject *kobj, struct attribute *attr,
                        rv = -EBUSY;
                else
                        rv = entry->store(rdev, page, length);
-               mddev_unlock(rdev->mddev);
+               mddev_unlock(mddev);
        }
        return rv;
 }