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CVE-2022-50668
ext4: fix deadlock due to mbcache entry corruption
Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix deadlock due to mbcache entry corruption When manipulating xattr blocks, we can deadlock infinitely looping inside ext4_xattr_block_set() where we constantly keep finding xattr block for reuse in mbcache but we are unable to reuse it because its reference count is too big. This happens because cache entry for the xattr block is marked as reusable (e_reusable set) although its reference count is too big. When this inconsistency happens, this inconsistent state is kept indefinitely and so ext4_xattr_block_set() keeps retrying indefinitely. The inconsistent state is caused by non-atomic update of e_reusable bit. e_reusable is part of a bitfield and e_reusable update can race with update of e_referenced bit in the same bitfield resulting in loss of one of the updates. Fix the problem by using atomic bitops instead. This bug has been around for many years, but it became *much* easier to hit after commit 65f8b80053a1 ("ext4: fix race when reusing xattr blocks").

INFO

Published Date :

Dec. 9, 2025, 4:17 p.m.

Last Modified :

Dec. 9, 2025, 6:37 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2022-50668 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Solution
Address race condition in ext4 by using atomic bit operations for xattr block manipulation.
  • Update the Linux kernel to a version that includes the fix.
  • Ensure kernel recompilation incorporates atomic bitops for xattr handling.
  • Test the system to confirm deadlock resolution in ext4.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2022-50668.

URL Resource
https://git.kernel.org/stable/c/127b80cefb941a81255c72f11081123f3a705369
https://git.kernel.org/stable/c/1be16a0c2f10186df505e28b0cc92d7f3366e2a8
https://git.kernel.org/stable/c/5bc0b2fda4b47c86278f7c6d30c211f425bf51cf
https://git.kernel.org/stable/c/a44e84a9b7764c72896f7241a0ec9ac7e7ef38dd
https://git.kernel.org/stable/c/af53065276376750dfac35a7248af18806404c5d
https://git.kernel.org/stable/c/cc1538c693d25e282bed8c54b65c914a04023a78
https://git.kernel.org/stable/c/efaa0ca678f56d47316a08030b2515678cebbc50
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2022-50668 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2022-50668 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2022-50668 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2022-50668 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Dec. 09, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: ext4: fix deadlock due to mbcache entry corruption When manipulating xattr blocks, we can deadlock infinitely looping inside ext4_xattr_block_set() where we constantly keep finding xattr block for reuse in mbcache but we are unable to reuse it because its reference count is too big. This happens because cache entry for the xattr block is marked as reusable (e_reusable set) although its reference count is too big. When this inconsistency happens, this inconsistent state is kept indefinitely and so ext4_xattr_block_set() keeps retrying indefinitely. The inconsistent state is caused by non-atomic update of e_reusable bit. e_reusable is part of a bitfield and e_reusable update can race with update of e_referenced bit in the same bitfield resulting in loss of one of the updates. Fix the problem by using atomic bitops instead. This bug has been around for many years, but it became *much* easier to hit after commit 65f8b80053a1 ("ext4: fix race when reusing xattr blocks").
    Added Reference https://git.kernel.org/stable/c/127b80cefb941a81255c72f11081123f3a705369
    Added Reference https://git.kernel.org/stable/c/1be16a0c2f10186df505e28b0cc92d7f3366e2a8
    Added Reference https://git.kernel.org/stable/c/5bc0b2fda4b47c86278f7c6d30c211f425bf51cf
    Added Reference https://git.kernel.org/stable/c/a44e84a9b7764c72896f7241a0ec9ac7e7ef38dd
    Added Reference https://git.kernel.org/stable/c/af53065276376750dfac35a7248af18806404c5d
    Added Reference https://git.kernel.org/stable/c/cc1538c693d25e282bed8c54b65c914a04023a78
    Added Reference https://git.kernel.org/stable/c/efaa0ca678f56d47316a08030b2515678cebbc50
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.