CVE-2025-40196
BaseFortify
Publication date: 2025-11-12
Last updated on: 2025-11-14
Assigner: kernel.org
Description
Description
CVSS Scores
EPSS 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 in the Linux kernel involves a kernel panic caused by a mismatch in workqueue flags during quota release work. Specifically, when a sync call triggers writeback on an opened file, and the f2fs filesystem needs to balance at the sync path, the quota_release_work is flushed. By default, quota_release_work is queued to the 'events_unbound' workqueue, which lacks the WQ_MEM_RECLAIM flag. During f2fs balance, the writeback workqueue tries to flush quota_release_work, causing a kernel panic due to MEM_RECLAIM flag mismatch errors. The fix creates a dedicated workqueue with the WQ_MEM_RECLAIM flag for quota_release_work to prevent this panic.
How can this vulnerability impact me? :
This vulnerability can cause the Linux kernel to panic and crash when certain filesystem operations involving quota release and f2fs balancing occur. This can lead to system instability, unexpected reboots, potential data loss, and downtime, affecting system availability and reliability.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring for kernel panic messages related to quota_release_work and workqueue flushing, especially if panic_on_warn is set. Look for kernel logs containing warnings like 'WARNING: CPU: ... check_flush_dependency' and kernel panic messages mentioning 'kernel: panic_on_warn set'. You can check kernel logs using commands such as 'dmesg | grep -i quota_release_work' or 'journalctl -k | grep -i panic'.
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation involves applying the patch that creates a dedicated workqueue with the WQ_MEM_RECLAIM flag for quota_release_work, as this resolves the kernel panic issue. Until the patch is applied, avoid triggering sync calls on opened files that cause writeback with WB_REASON_SYNC on f2fs filesystems, or disable panic_on_warn to prevent kernel panic on warnings.