CVE-2025-21980: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: sched: address a potential NULL pointer dereference in the GRED scheduler. If kzalloc in gred_init returns a NULL pointer, the code follows the error handling path, invoking gred_destroy. This, in turn, calls gred_offload, where memset could receive a NULL pointer as input, potentially leading to a kernel crash. When table->opt is NULL in gred_init(), gred_change_table_def() is not called yet, so it is not necessary to call ->ndo_setup_tc() in gred_offload().

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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-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.16 — 6.1.132
linux	linux_kernel	6.2 — 6.6.84
linux	linux_kernel	6.7 — 6.12.20
linux	linux_kernel	6.13 — 6.13.8
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0f0a152957d64ce45b4c27c687e7d087e8f45079 https://git.kernel.org/stable/c/115ef44a98220fddfab37a39a19370497cd718b9 https://git.kernel.org/stable/c/5f996b4f80c2cef1f9c77275055e7fcba44c9199 https://git.kernel.org/stable/c/68896dd50180b38ea552e49a6a00b685321e5769 https://git.kernel.org/stable/c/d02c9acd68950a444acda18d514e2b41f846cb7f

Other References

https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

Frequently Asked Questions

What is CVE-2025-21980? +

In the Linux kernel, the following vulnerability has been resolved: sched: address a potential NULL pointer dereference in the GRED scheduler. If kzalloc in gred_init returns a NULL pointer, the code follows the error handling path, invoking gred_destroy. This, in turn, calls gred_offload, where memset could receive a NULL pointer as input, potentially leading to a kernel crash. When table->opt is NULL in gred_init(), gred_change_table_def() is not called yet, so it is not necessary to call ->ndo_setup_tc() in gred_offload(). It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21980? +

CVE-2025-21980 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-2025-21980? +

CVE-2025-21980 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-2025-21980? +

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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