CVE-2025-38492
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-07-28

Last updated on: 2025-11-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix race between cache write completion and ALL_QUEUED being set When netfslib is issuing subrequests, the subrequests start processing immediately and may complete before we reach the end of the issuing function. At the end of the issuing function we set NETFS_RREQ_ALL_QUEUED to indicate to the collector that we aren't going to issue any more subreqs and that it can do the final notifications and cleanup. Now, this isn't a problem if the request is synchronous (NETFS_RREQ_OFFLOAD_COLLECTION is unset) as the result collection will be done in-thread and we're guaranteed an opportunity to run the collector. However, if the request is asynchronous, collection is primarily triggered by the termination of subrequests queuing it on a workqueue. Now, a race can occur here if the app thread sets ALL_QUEUED after the last subrequest terminates. This can happen most easily with the copy2cache code (as used by Ceph) where, in the collection routine of a read request, an asynchronous write request is spawned to copy data to the cache. Folios are added to the write request as they're unlocked, but there may be a delay before ALL_QUEUED is set as the write subrequests may complete before we get there. If all the write subreqs have finished by the ALL_QUEUED point, no further events happen and the collection never happens, leaving the request hanging. Fix this by queuing the collector after setting ALL_QUEUED. This is a bit heavy-handed and it may be sufficient to do it only if there are no extant subreqs. Also add a tracepoint to cross-reference both requests in a copy-to-request operation and add a trace to the netfs_rreq tracepoint to indicate the setting of ALL_QUEUED.
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Meta Information
Published
2025-07-28
Last Modified
2025-11-19
Generated
2026-05-07
AI Q&A
2025-07-28
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38492
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-362 The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
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 netfs subsystem. When netfslib issues asynchronous subrequests, these subrequests may complete before the main issuing function finishes and sets a flag (NETFS_RREQ_ALL_QUEUED) indicating no more subrequests will be issued. If all subrequests complete before this flag is set, the final collection and cleanup process may never be triggered, causing the request to hang indefinitely.


How can this vulnerability impact me? :

The vulnerability can cause requests in the netfs subsystem to hang indefinitely due to the race condition between subrequest completion and the ALL_QUEUED flag being set. This can lead to stalled operations, potentially impacting system stability or performance when using affected features like Ceph's copy2cache.


What immediate steps should I take to mitigate this vulnerability?

Apply the patch or update to the Linux kernel version that includes the fix for this vulnerability, which addresses the race condition in netfs by queuing the collector after setting ALL_QUEUED. This prevents requests from hanging due to incomplete collection. Monitoring or tracing using the added tracepoints (netfs_rreq and copy-to-request tracepoints) may help in diagnosing related issues.


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