CVE-2025-71132
Description
A locking context bug was found in the Linux kernel's smc91x Ethernet driver on PREEMPT_RT kernels. The smc_special_trylock() function disables IRQs but smc_special_unlock() does not properly restore IRQs on PREEMPT_RT. This mismatch causes RCU read unlock to fail in __dev_queue_xmit(), triggering a "workqueue leaked atomic, lock or RCU" warning.
Statement
This vulnerability specifically affects PREEMPT_RT kernel configurations with smc91x network hardware, typically found in embedded ARM systems and emulated environments like ARM FVP. Standard kernel builds are not affected. The issue causes kernel warnings and potential network subsystem instability but is limited to specialized real-time configurations.
Mitigation
To mitigate this issue, prevent the smc91x module from being loaded if this legacy Ethernet hardware is not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.7 | 5.5 | 7.5 |
| Attack Vector | Local | Local | Network |
| Attack Complexity | High | Low | Low |
| Privileges Required | Low | Low | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Other
Technical Impact: Modify Application Data; Read Application Data; Alter Execution Logic
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