CVE-2025-68807
BaseFortify
Publication date: 2026-01-13
Last updated on: 2026-01-14
Assigner: kernel.org
Description
Description
CVSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a race condition in the Linux kernel's block layer involving the writeback throttling (WBT) mechanism. Specifically, when the function wbt_enable_default() is moved out of queue freezing in elevator_change(), it can cause the WBT inflight counter to become negative (-1). This happens because wbt_enable_default() can race with IO submission, allowing the counter to be decremented before it is properly initialized. As a result, tasks get stuck or hung in the writeback path, waiting indefinitely due to the inconsistent state of the counter.
How can this vulnerability impact me? :
This vulnerability can cause tasks in the Linux kernel to hang or become stuck during IO operations, specifically in the writeback path. This can lead to system instability or degraded performance because IO submissions may not proceed correctly, potentially causing delays or hangs in processes that rely on disk IO.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability manifests as hung tasks in the writeback path with the inflight counter becoming negative (-1). You can detect it by checking for hung task warnings in kernel logs, specifically messages showing tasks stuck in wbt_wait() and negative inflight counters such as: rq_wait[0]: inflight: -1 has_waiters: True Look for kernel log entries with call traces including rq_qos_wait, wbt_wait, __rq_qos_throttle, and blk_mq_submit_bio. Commands to check kernel logs include: dmesg | grep -i wbt_wait journalctl -k | grep -i wbt_wait or searching for hung task warnings related to block IO submission in system logs.
What immediate steps should I take to mitigate this vulnerability?
The vulnerability is fixed by ensuring proper initialization of the writeback throttling (WBT) inflight counter before IO submission. Immediate mitigation involves updating the Linux kernel to a version that includes the fix, which splits wbt_enable_default() and moves wbt_init() to be called during queue registration, preventing the inflight counter from becoming negative. Until the patch is applied, monitoring for hung tasks and avoiding heavy IO workloads that trigger the race condition may reduce impact, but the definitive mitigation is applying the kernel update containing the fix.