CVE-2022-49873: bpf: Fix wrong reg type conversion in release_reference()

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: 2025-05-01 · updated 2026-06-17
Weakness: CWE-704

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix wrong reg type conversion in release_reference() Some helper functions will allocate memory. To avoid memory leaks, the verifier requires the eBPF program to release these memories by calling the corresponding helper functions. When a resource is released, all pointer registers corresponding to the resource should be invalidated. The verifier use release_references() to do this job, by apply __mark_reg_unknown() to each relevant register. It will give these registers the type of SCALAR_VALUE. A register that will contain a pointer value at runtime, but of type SCALAR_VALUE, which may allow the unprivileged user to get a kernel pointer by storing this register into a map. Using __mark_reg_not_init() while NOT allow_ptr_leaks can mitigate this problem.

Affected products

Linux kernel: from 4.20 before 5.10.155; from 5.11 before 5.15.79; from 5.16 before 6.0.9; 6.1-rc1, 6.1-rc2, 6.1-rc3, 6.1-rc4 — fixed in 5.10.155, 5.15.79, 6.0.9

How to fix

Upgrade to a fixed version: Linux kernel 5.10.155, 5.15.79, 6.0.9. Check the vendor advisory for mitigations.

References

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