A security-relevant race between mremap() and THP code has been discovered. Reaching the buggy code typically requires the ability to create unprivileged namespaces. The bug leads to installing physical address 0 as a page table, which is likely exploitable in several ways: For example, triggering the bug in multiple processes can probably lead to unintended page table sharing, which probably can lead to stale TLB entries pointing to freed pages. Continue reading...
