The MITRE CVE dictionary describes this issue as:
The compat_alloc_user_space functions in include/asm/compat.h files in the Linux kernel before 2.6.36-rc4-git2 on 64-bit platforms do not properly allocate the userspace memory required for the 32-bit compatibility layer, which allows local users to gain privileges by leveraging the ability of the compat_mc_getsockopt function (aka the MCAST_MSFILTER getsockopt support) to control a certain length value, related to a "stack pointer underflow" issue, as exploited in the wild in September 2010.
Find out more about CVE-2010-3081 from the
MITRE CVE dictionary dictionary and
More information can be found in this kbase: https://access.redhat.com/kb/docs/DOC-40265.