CVE-2024-42102 Revert "mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again"
An integer overflow in Linux kernel dirty throttling logic can cause a divide-by-zero error, leading to a system crash or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-42102?
CVE-2024-42102 is a medium-severity vulnerability in Linux kernel, published on 30 Jul 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
Revert "mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again"
Patch series "mm: Avoid possible overflows in dirty throttling".
Dirty throttling logic assumes dirty limits in page units fit into 32-bits. This patch series makes sure this is true (see patch 2/2 for more details).
This patch (of 2):
This reverts commit 9319b647902cbd5cc884ac08a8a6d54ce111fc78.
The commit is broken in several ways. Firstly, the removed (u64) cast from the multiplication will introduce a multiplication overflow on 32-bit archs if wb_thresh * bg_thresh >= 1<<32 (which is actually common - the default settings with 4GB of RAM will trigger this). Secondly, the div64_u64() is unnecessarily expensive on 32-bit archs. We have div64_ul() in case we want to be safe & cheap. Thirdly, if dirty thresholds are larger than 1<<32 pages, then dirty balancing is going to blow up in many other spectacular ways anyway so trying to fix one possible overflow is just moot.
Weakness: CWE-369
Which versions are affected by CVE-2024-42102?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-42102?
Apply the vendor's patch.
Is CVE-2024-42102 being exploited?
There is no known exploitation of CVE-2024-42102 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-47934, BELL-CVE-2024-42102, DEBIAN-CVE-2024-42102, GHSA-3cf4-3gwv-8jwp, UBUNTU-CVE-2024-42102.