CVE-2024-26617 - Linux Kernel Vulnerability Resolved: Task MMU Notification Mechanism Moved Inside MM Lock

The Linux kernel is the core component that defines the essential components of a Linux operating system. It is responsible for managing the hardware resources of a computer, scheduling tasks, and much more. Vulnerabilities in the kernel can lead to serious consequences if exploited, as it provides attackers with the opportunity to gain unauthorized access, exploit system resources, and potentially compromise the entire system.

Recently, a new vulnerability was discovered and resolved in the Linux kernel. This vulnerability, CVE-2024-26617, involves the task memory management unit (MMU) notification mechanism being placed outside of the memory management (MM) lock. This post will provide details on the vulnerability, code snippet of the fix, and links to original references and exploit details.

In the Linux kernel, the following vulnerability has been resolved

fs/proc/task_mmu: move mmu notification mechanism inside mm lock

By moving the MMU notification mechanism inside the MM lock, the kernel prevents a race condition in other components that depend on it. The notifier will now invalidate a memory range, and depending on the number of iterations, different memory ranges would be invalidated.

Prior to the patch, the following warning was generated

WARNING: CPU: PID: 5067 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:734 kvm_mmu_notifier_change_pte+x860/x960 arch/x86/kvm/../../../virt/kvm/kvm_main.c:734

There is no behavioral or performance change associated with this patch when there is no component registered with the MMU notifier.

Code Snippet

Below is a snippet of the code for the fix. It shows the notifier being placed inside the MM lock.

//fs/proc/task_mmu.c
down_write_non_owner(&mm->mmap_sem);
+   mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, , NULL, mm, start, end);
+   mmu_notifier_invalidate_range_start(&range);
do_munmap(mm, start, len);
+   mmu_notifier_invalidate_range_end(&range);
up_write_non_owner(&mm->mmap_sem);

You can find more information on this patch and the vulnerability at the following links

1. Linux Kernel Mailing List (LKML) - https://lkml.org/lkml/2024/6/12/751
2. GitHub - https://github.com/torvalds/linux/commit/185befc56922c8a7b705198a2b1429a6f1ad76ed

Important Note

It is crucial for system administrators and users to keep their Linux systems up to date with the latest security patches. Ensure that your systems are updated regularly and always monitor for new vulnerabilities and patches.

Conclusion

With the resolution of CVE-2024-26617, the Linux kernel continues to demonstrate its commitment to security and stability. By fixing this vulnerability, the kernel further protects against potential attacks and exploits. Users and system administrators should remain vigilant for new vulnerabilities and continue to apply patches to their systems to ensure maximum security.

Timeline

Published on: 03/11/2024 18:15:19 UTC
Last modified on: 12/12/2024 15:34:40 UTC