CVE-2026-64062: netfs: Fix potential deadlock in write-through mode
In the Linux kernel, the following vulnerability has been resolved:
netfs: Fix potential deadlock in write-through mode
Fix netfsadvancewritethrough() to always unlock the supplied folio and to mark it dirty if it isn't yet written to the end. Unfortunately, it can't be marked for writeback until the folio is done with as that may cause a deadlock against mmapped reads and writes.
Even though it has been marked dirty, premature writeback can't occur as the caller is holding both inode->irwsem (which will prevent concurrent truncation, fallocation, DIO and other writes) and ictx->wblock (which will cause flushing to wait and writeback to skip or wait).
Note that this may be easier to deal with once the queuing of folios is split from the generation of subrequests.
Affected Software
Remediation
Event History
Frequently Asked Questions
What access would an attacker need to trigger this issue?
The CVSS vector indicates local access and low privileges are required. No user interaction is required.
What is the practical impact if the issue is triggered?
The reported impact is a potential deadlock in netfs write-through mode, with availability impact rated High. The CVSS vector reports no confidentiality or integrity impact.
Which activity and configuration are implicated?
The issue concerns Linux kernel netfs write-through mode during folio write handling. The provided information does not state whether write-through mode is enabled by default.
What can be done if patching cannot happen immediately?
The provided data identifies write-through mode as the affected condition, but does not provide a documented workaround or mitigation. A patch is available.