Medium [CVE-2026-74365] Handle preemption in BTT lane acquisition
This medium-severity Red Hat Linux advisory covers CVE-2026-74365 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: nvdimm/btt: Handle preemption in BTT lane acquisition BTT lanes serialize access to per-lane metadata and workspace state during BTT I/O. The btt-check unit test reports data mismatches during BTT writes due to a race in lane acquisition that can lead to silent data corruption.
The existing lane model uses a spinlock together with a per-CPU recursion count. That recursion model stopped being valid after BTT lanes became preemptible: another task can run on the same CPU, observe a non-zero recursion count, bypass locking, and use the same lane concurrently.
BTT lanes are also held across arena_write_bytes() calls. That path reaches nsio_rw_bytes(), which flushes writes with nvdimm_flush().
Some provider flush callbacks can sleep, making a spinlock the wrong primitive for the lane lifetime. Replace the spinlock-based recursion model with a dynamically allocated per-lane mutex array and take the lane lock unconditionally.
Add might_sleep() to catch any future atomic-context caller. A flaw was found in the Linux kernel's NVDIMM Block Translation Table (BTT) subsystem.
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-366.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9.
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 2 hours 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 2 hours 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 2 hours ago·verify at source
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