On Mon, 20 Feb 2017 13:29:46 +0200 Elena Reshetova <elena.reshet...@intel.com> wrote:
> Now when new refcount_t type and API are finally merged > (see include/linux/refcount.h), the following > patches convert various refcounters in the ipc susystem from atomic_t > to refcount_t. By doing this we prevent intentional or accidental > underflows or overflows that can led to use-after-free vulnerabilities. > > The below patches are fully independent and can be cherry-picked separately. > Since we convert all kernel subsystems in the same fashion, resulting > in about 300 patches, we have to group them for sending at least in some > fashion to be manageable. Please excuse the long cc list. Again, the refcount_t operations are much more expensive than the bare atomic_t operations. I'm reluctant to merge any of these conversions without either a) a convincing demonstration that the performance impact is sufficiently small (ie: unmeasurable) or b) a compile-time option to disable the refcount_t operations (make them generate the same code as the bare atomic_t ops). Along with some suitably reliable means of preventing people from accidentally enabling the debug code in production builds.
