CVE-2022-50367
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: fs: fix UAF/GPF bug in nilfs_mdt_destroy In alloc_inode, inode_init_always() could return -ENOMEM if security_inode_alloc() fails, which causes inode->i_private uninitialized. Then nilfs_is_metadata_file_inode() returns true and nilfs_free_inode() wrongly calls nilfs_mdt_destroy(), which frees the uninitialized inode->i_private and leads to crashes(e.g., UAF/GPF). Fix this by moving security_inode_alloc just prior to this_cpu_inc(nr_inodes)
Statement
This patch fixes a use-after-free/GPF bug in the NILFS2 metadata handling. When security_inode_alloc() failed, an uninitialized inode->i_private pointer could later be freed by nilfs_mdt_destroy(), leading to memory corruption or crashes. You can reproduce this issue on systems using NILFS, because the crash path involves nilfs_mdt_destroy() freeing inode->i_private when security_inode_alloc() fails. On other filesystems the same cleanup path does not run, so accidental freeing of that uninitialized field is far less likely. Consequently, systems not using NILFS are at much lower risk unless they have other code that similarly frees inode->i_private. For the all versions of the Red Hat Enterprise Linux the config param CONFIG_NILFS2_FS disabled, so with the known scenario of attack it is not affected.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | High | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
