# Linux 7.4 Core MM tree lands fixes for data loss, UAF, and information leaks

> **Key takeaway:** The second Core MM pull request for Linux 7.4-rc2 delivers stable-worthy fixes across THP, GUP, KSM, memfd, and shmem subsystems, with multiple issues reported by Anthropic.

**Published:** 2026-11-05T11:05:02+00:00 
**Source:** Phoronix Benchmarks & Drivers 
**Category:** kernel-os 
**Canonical URL:** https://fosswire.org/news/linux-74-core-mm-tree-lands-fixes-for-data-loss-uaf-and-info.html 

## Summary
The newly established Core MM tree for the Linux 7.4 kernel cycle has submitted its second pull request, delivering a substantial batch of memory management fixes targeting long-standing bugs rather than recent regressions. David Hildenbrand of Arm, who is helping oversee this initiative, noted that most of these fixes address 'nasty long-standing bugs' and are considered stable-worthy backport candidates. The patches span core subsystems including Transparent Huge Pages, Get User Pages, Kernel Samepage Merging, userfaultfd, shared memory, and hugetlb.

The fixes were predominantly reported by Anthropic, with additional issues discovered during rework of proposed patches and through standard mailing list discussion. The changes address serious defect classes: information leaks via memfd pinning, out-of-bounds writes in GUP, data loss in shmem and KSM, corruption in huge page mappings, incorrect TLB flushing, and multiple use-after-free vulnerabilities with particular attention to shmem swap handling. The pull request remains pending on the Linux kernel mailing list.

## Subsystem fixes in the 7.4-rc2 Core MM pull
- **memfd and GUP security:** Fixes prevent information leaks through memfd pinning and eliminate out-of-bounds write vulnerabilities in the Get User Pages mechanism.
- **Data loss prevention:** Corrects data loss conditions in shmem, THP collapse operations, KSM page merging, and memfd pinning scenarios.
- **Huge page mapping integrity:** Repairs corruption and reference-counting errors in huge PMD/PUD mappings, plus incorrect TLB flushing and unmapping behavior.
- **Memory reclaim and swap stability:** Addresses use-after-free bugs, deadlocks, and unkillable loops with concentrated fixes for shmem swap handling paths.
- **Execution seal and userfaultfd:** Enforces execution-seal properly for memfd including hugetlb-backed instances, and fixes accounting, quota, and userfaultfd registration/unregistration handling.

## Why it matters
These stable-worthy fixes will flow to enterprise and long-term support kernels through the standard backport process, reducing exposure to data corruption and privilege escalation paths in container and virtualization workloads that rely heavily on memfd, KSM, and userfaultfd. For Linux distribution maintainers and systems administrators, the concentration of fixes in shmem and swap handling is particularly relevant given the widespread use of tmpfs for /tmp and container runtime storage.