CVE-2023-52497 erofs: fix lz4 inplace decompression
A memory corruption flaw in the Linux kernel's EROFS filesystem allows data corruption or denial of service during LZ4 decompression on specific hardware.
- 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-2023-52497?
CVE-2023-52497 is a high-severity memory corruption vulnerability in Linux kernel, published on 29 Feb 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:
erofs: fix lz4 inplace decompression
Currently EROFS can map another compressed buffer for inplace decompression, that was used to handle the cases that some pages of compressed data are actually not in-place I/O.
However, like most simple LZ77 algorithms, LZ4 expects the compressed data is arranged at the end of the decompressed buffer and it explicitly uses memmove() to handle overlapping: __________________________________________________________ |_ direction of decompression --> ____ |_ compressed data _|
Although EROFS arranges compressed data like this, it typically maps two individual virtual buffers so the relative order is uncertain. Previously, it was hardly observed since LZ4 only uses memmove() for short overlapped literals and x86/arm64 memmove implementations seem to completely cover it up and they don't have this issue. Juhyung reported that EROFS data corruption can be found on a new Intel x86 processor. After some analysis, it seems that recent x86 processors with the new FSRM feature expose this issue with "rep movsb".
Let's strictly use the decompressed buffer for lz4 inplace decompression for now. Later, as an useful improvement, we could try to tie up these two buffers together in the correct order.
Weakness: CWE-787
Which versions are affected by CVE-2023-52497?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-52497?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2023-52497 being exploited?
There is no known exploitation of CVE-2023-52497 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-52497, DEBIAN-CVE-2023-52497, GHSA-7hmq-6483-qr84, UBUNTU-CVE-2023-52497.