The part_shift in RingData could be negative

[autumn wang]

In common/ring/build.py, during line 146-151:

            if not self._replica2part2dev:
                self._ring = RingData([], devs, 32 - self.part_power)
            else:
                self._ring = \
                RingData([array('H', p2d) for p2d in self._replica2part2dev],
                         devs, 32 - self.part_power)

If the "part_power" in class RingBuilder is larger than 32, the value of " part_shift' in class RingData will be negative.
This will cause the following code failure, which is in line 133 of file common/ring/ring.py:
part = unpack_from('>I', key)[0] >> self._part_shift

Suggest: Add value checking in RingBuilder.__init__

[Pete Zaitcev (zaitcev)]

I am unable to confirm it properly because my swif-ring-builder runs out of RAM when trying to rebalance a ring with 33 power :-) Still, obviously it's a problem.

[Bavirisetty Ramya (bavirisetty-ramya)]

Hi
I checked up the part_power value in the __init__ method of the RingBuilder class and raised a value error exception if the part_power is greater than 32 as below:
def __init__(self, part_power, replicas, min_part_hours):
        self.part_power = part_power
        self.replicas = replicas
        self.min_part_hours = min_part_hours
        self.parts = 2 ** self.part_power
        self.devs = []
        self.devs_changed = False
        self.version = 0
        if part_power > 32:
            raise ValueError("partpower should be less than 32")

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/8471

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24613

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24613
Committed: http://github.com/openstack/swift/commit/d42a78a3aa138ca14e1b06555ae649971799e618
Submitter: Jenkins
Branch: master

commit d42a78a3aa138ca14e1b06555ae649971799e618
Author: Samuel Merritt <email address hidden>
Date: Sun Mar 17 15:07:20 2013 -0700

    Basic ring builder validation.

    This prevents people from creating bogus ring builder files.

    Example: "swift-ring-builder object.builder create 33 0.9 -4".

    Fixes bug 924577.

    Change-Id: I7bfc04f7fa5f55f70a4eaae96c414f6b2872e283