Medium [CVE-2026-64062] Fix potential deadlock in write-through mode
This medium-severity Red Hat Linux advisory covers CVE-2026-64062 affecting Red Hat Enterprise Linux 10, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix potential deadlock in write-through mode Fix netfs_advance_writethrough() 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->i_rwsem (which will prevent concurrent truncation, fallocation, DIO and other writes) and ictx->wb_lock (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. A flaw was found in the Linux kernel's network filesystem (netfs) component.
Specifically, a vulnerability in the netfs_advance_writethrough() function, when operating in write-through mode, can lead to a system deadlock. This occurs because the function may not consistently unlock memory pages (folios) or mark them as modified, preventing proper writeback operations.
Consequently, concurrent memory-mapped (mmapped) read and write operations can cause the system to become unresponsive. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-833.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
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