CVE-2025-21980: sched: address a potential NULL pointer dereference in the GRED scheduler.

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-01 · updated 2026-06-17
Weakness: CWE-476

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().

Affected products

Linux kernel: from 5.16 before 6.1.132; from 6.2 before 6.6.84; from 6.7 before 6.12.20; from 6.13 before 6.13.8; 6.14-rc1, 6.14-rc2, 6.14-rc3, 6.14-rc4, 6.14-rc5, 6.14-rc6 — fixed in 6.1.132, 6.12.20, 6.13.8, 6.6.84

How to fix

Upgrade to a fixed version: Linux kernel 6.1.132, 6.12.20, 6.13.8, 6.6.84. Check the vendor advisory for mitigations.

References

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