A security flaw was found in the Linux kernel that there is a way to arbitrary change zero page memory. Zero page is a page which kernel maps into virtual address space on read page fault if the page was not allocated before. Kernel has one zero page which used everywhere. Programs that map 0 page are affected and code execution can be gained. Upon running the exploit the system may become unusable as the linker memory pages gets tainted. Furthermore, if the right code is put in the 0 page, code execution is possible.
Acknowledgments: Name: Kirill A. Shutemov (Intel)
Upstream patch: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6b7339f4c31ad69c8e9c0b2859276e22cf72176d
Statement: This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5. This has been rated as having Low security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/. This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 6, 7 and MRG-2. Future Linux kernel updates for the respective releases might address this issue.