Medium [CVE-2026-74379] account for partial discontiguous resource upon removal

In the Linux kernel, the following vulnerability has been resolved: dax/kmem: account for partial discontiguous resource upon removal When dev_dax_kmem_probe() partially succeeds (at least one range is mapped) but a subsequent range fails request_mem_region() or add_memory_driver_managed(), the probe silently continues, ultimately returning success, but with the corresponding range resource NULL'ed out. dev_dax_kmem_remove() iterates over all dax_device ranges regardless of if the underlying resource exists.

When remove_memory() is called later, it returns 0 because the memory was never added which causes dev_dax_kmem_remove() to incorrectly assume the (nonexistent) resource can be removed and attempts cleanup on a NULL pointer.

Fix this by skipping these ranges altogether, noting that these cases are considered success, such that the cleanup is still reached when all actually-added ranges are successfully removed. This vulnerability occurs when the system attempts to remove a memory resource that was not fully initialized, leading to an attempt to access a null pointer.

A local attacker could potentially trigger this condition, causing the system to crash and resulting in a Denial of Service (DoS). 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-476.