CVE-2025-39784
BaseFortify
Publication date: 2025-09-11
Last updated on: 2025-11-25
Assigner: kernel.org
Description
Description
CVSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | From 5.15.160 (inc) to 5.16 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-NVD-CWE-noinfo |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability occurs in the Linux kernel's PCIe link speed calculation during a link retrain failure. When the function pcie_failed_link_retrain() fails to retrain the PCIe link, it attempts to revert to the previous link speed. However, it incorrectly calculates the speed from the Link Control 2 register without masking out bits that are not related to speed. This causes the conversion function PCIE_LNKCTL2_TLS2SPEED() to return an unknown speed value (PCI_SPEED_UNKNOWN), which leads to warnings and errors in the kernel, potentially indicating a broken device or non-functional downstream link.
How can this vulnerability impact me? :
The impact of this vulnerability is that the PCIe link retrain failure handling may incorrectly report the link speed as unknown, causing warning messages and potentially indicating a broken or non-functional PCIe device link. This could lead to instability or degraded performance in systems relying on PCIe devices, as the kernel may not correctly manage link speeds after retrain failures.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring system logs for warnings related to PCIe link retraining failures. Specifically, look for messages similar to: 'WARNING: CPU: ... pcie_set_target_speed' and 'retraining failed' in the kernel logs. You can use the command 'dmesg | grep -i pcie' or 'journalctl -k | grep -i pcie' to find such warnings indicating the issue.
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation involves updating the Linux kernel to a version that includes the fix for this vulnerability, which masks out non-speed bits in the link speed calculation to prevent incorrect PCI_SPEED_UNKNOWN values and related warnings. Until the update is applied, monitoring for the warning messages and avoiding operations that trigger PCIe link retraining failures may help reduce impact.