CVE-2026-74365: Linux

High severity, CVSS 7.3. EPSS: 0.2% chance of exploitation in the next 30 days.

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. Found with the ndctl unit test btt-check.sh.

Affected products

• Linux Linux: from 6.1.63, before 6.1.178 (fixed in 6.1.178); from 6.6.2, before 6.6.145 (fixed in 6.6.145); from 4.19.299, before 4.20 (fixed in 4.20); from 5.4.261, before 5.5 (fixed in 5.5); from 5.10.201, before 5.11 (fixed in 5.11); from 5.15.139, before 5.16 (fixed in 5.16); …

Published 2026-08-15. Last modified 2026-08-17.