[Maverick] [CVE-2011-0695] [PATCH 1/2] IB/cm: Bump reference count on cm_id before invoking callback, CVE-2011-0695

[Brad Figg]

On 04/25/2011 05:53 PM, Tim Gardner wrote:
> On 04/25/2011 01:29 PM, Brad Figg wrote:
>> From: Sean Hefty<sean.hefty at intel.com>
>>
>> CVE-2011-0695
>>
>> BugLink: http://bugs.launchpad.net/bugs/770369
>>
>> When processing a SIDR REQ, the ib_cm allocates a new cm_id. The
>> refcount of the cm_id is initialized to 1. However, cm_process_work
>> will decrement the refcount after invoking all callbacks. The result
>> is that the cm_id will end up with refcount set to 0 by the end of the
>> sidr req handler.
>>
>> If a user tries to destroy the cm_id, the destruction will proceed,
>> under the incorrect assumption that no other threads are referencing
>> the cm_id. This can lead to a crash when the cm callback thread tries
>> to access the cm_id.
>>
>> This problem was noticed as part of a larger investigation with kernel
>> crashes in the rdma_cm when running on a real time OS.
>>
>> Signed-off-by: Sean Hefty<sean.hefty at intel.com>
>> Acked-by: Doug Ledford<dledford at redhat.com>
>> Cc:<stable at kernel.org>
>> Signed-off-by: Roland Dreier<roland at purestorage.com>
>>
>> (cherry-picked from commit 29963437a48475036353b95ab142bf199adb909e)
>> Signed-off-by: Brad Figg<brad.figg at canonical.com>
>> ---
>> drivers/infiniband/core/cm.c | 1 +
>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
>> index 64e0903..1d9616b 100644
>> --- a/drivers/infiniband/core/cm.c
>> +++ b/drivers/infiniband/core/cm.c
>> @@ -2989,6 +2989,7 @@ static int cm_sidr_req_handler(struct cm_work *work)
>> goto out; /* No match. */
>> }
>> atomic_inc(&cur_cm_id_priv->refcount);
>> + atomic_inc(&cm_id_priv->refcount);
>> spin_unlock_irq(&cm.lock);
>>
>> cm_id_priv->id.cm_handler = cur_cm_id_priv->id.cm_handler;
>
> I'm a bit curious how you got these 2 patches to apply 'cause they were released with 2.6.35-29.51. Did you start with master instead of master-next ?
>
> rtg

That's a really good question. I patched an old local repo. I got distracted
working on these and thought I'd updated my repo but had not. Thanks for
catching this and sorry to waste everyone's time.

Brad
-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com