CVE-2024-56755: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING In fscache_create_volume(), there is a missing memory barrier between the bit-clearing operation and the wake-up operation. This may cause a situation where, after a wake-up, the bit-clearing operation hasn't been detected yet, leading to an indefinite wait. The triggering process is as follows: [cookie1] [cookie2] [volume_work] fscache_perform_lookup fscache_create_volume fscache_perform_lookup fscache_create_volume fscache_create_volume_work cachefiles_acquire_volume clear_and_wake_up_bit test_and_set_bit test_and_set_bit goto maybe_wait goto no_wait In the above process, cookie1 and cookie2 has the same volume. When cookie1 enters the -no_wait- process, it will clear the bit and wake up the waiting process. If a barrier is missing, it may cause cookie2 to remain in the -wait- process indefinitely. In commit 3288666c7256 ("fscache: Use clear_and_wake_up_bit() in fscache_create_volume_work()"), barriers were added to similar operations in fscache_create_volume_work(), but fscache_create_volume() was missed. By combining the clear and wake operations into clear_and_wake_up_bit() to fix this issue.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-401 CWE-401

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.17 — 6.1.120
linux	linux_kernel	6.2 — 6.6.64
linux	linux_kernel	6.7 — 6.11.11
linux	linux_kernel	6.12 — 6.12.2

References

Advisories & Patches

https://git.kernel.org/stable/c/22f9400a6f3560629478e0a64247b8fcc811a24d https://git.kernel.org/stable/c/539fabba965e119b98066fc6ba5257b5eaf4eda2 https://git.kernel.org/stable/c/8beb682cc9a0798a280bbb95e3e41617237090b2 https://git.kernel.org/stable/c/8cc1df3113cb71a0df2c46dd5b102c9e11c8a8c6 https://git.kernel.org/stable/c/ddab02607eed9e415dc62fde421d4329e5345315

Other References

https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html

Frequently Asked Questions

What is CVE-2024-56755? +

In the Linux kernel, the following vulnerability has been resolved: netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING In fscache_create_volume(), there is a missing memory barrier between the bit-clearing operation and the wake-up operation. This may cause a situation where, after a wake-up, the bit-clearing operation hasn't been detected yet, leading to an indefinite wait. The triggering process is as follows: [cookie1] [cookie2] [volume_work] fscache_perform_lookup fscache_create_volume fscache_perform_lookup fscache_create_volume fscache_create_volume_work cachefiles_acquire_volume clear_and_wake_up_bit test_and_set_bit test_and_set_bit goto maybe_wait goto no_wait In the above process, cookie1 and cookie2 has the same volume. When cookie1 enters the -no_wait- process, it will clear the bit and wake up the waiting process. If a barrier is missing, it may cause cookie2 to remain in the -wait- process indefinitely. In commit 3288666c7256 ("fscache: Use clear_and_wake_up_bit() in fscache_create_volume_work()"), barriers were added to similar operations in fscache_create_volume_work(), but fscache_create_volume() was missed. By combining the clear and wake operations into clear_and_wake_up_bit() to fix this issue. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2024-56755? +

CVE-2024-56755 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-56755? +

CVE-2024-56755 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-56755? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2024-56755