A denial of service flaw was found in the way ibacm, an InfiniBand communication manager assistant, performed management of reference counts for multicast connections. The default reference count value for multicast connection is set to zero and when the multicast connection got released, an attempt was made to free it, possibly resulting in ibacm service / daemon crash.

Upstream patch: [1] http://git.openfabrics.org/git?p=~shefty/ibacm.git;a=commit;h=c7d28b35d64333c262de3ec972c426423dadccf9