CVE-2022-50746
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: erofs: validate the extent length for uncompressed pclusters syzkaller reported a KASAN use-after-free: https://syzkaller.appspot.com/bug?extid=2ae90e873e97f1faf6f2 The referenced fuzzed image actually has two issues: - m_pa == 0 as a non-inlined pcluster; - The logical length is longer than its physical length. The first issue has already been addressed. This patch addresses the second issue by checking the extent length validity.
Statement
In EROFS compressed layout code z_erofs_do_map_blocks handles plain uncompressed pclusters. A crafted filesystem image can provide an extent where the logical length map m_llen is larger than the physical length map m_plen. This breaks internal assumptions about valid mapping ranges and can cause subsequent code to access memory or buffers based on inconsistent lengths. Syzkaller reported a KASAN use after free in this area (read). A local attacker can mount or otherwise cause the kernel to parse a crafted EROFS image. In many environments mounting requires CAP_SYS_ADMIN. However parsing may also happen indirectly in privileged contexts such as system image handling.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 8.4 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
