Technical impact
The Linux kernel md bitmap module contains a race condition between bitmap_daemon_work() and __bitmap_resize() that can trigger a general protection fault during write_page() when the bitmap storage is resized concurrently with the daemon iterating over the same memory. The missing mutex protection leads to a use‑after‑free, which results in an unhandled kernel crash and a system reboot. The flaw falls under CWE-362 and CWE-825.
Affected Systems
All Linux kernel releases that include the md bitmap module without the introduced mutex lock are affected. The data does not specify an exact version range; therefore any kernel that has not applied the patch that adds the mutex protection around the bitmap update is vulnerable. The modified code is part of the mainline kernel and will be present in all distributions that ship the corresponding kernel version.
Risk and Exploitability
The CVSS score for this vulnerability is 4.7. The EPSS score is < 1%, indicating a very low but nonzero probability of exploitation. Based on the description, it is inferred that the flaw can be triggered by a local user with sufficient privileges to manipulate block devices, such as an individual with root access or a process operating within a virtual machine that controls the block layer. The crash only occurs while the kernel is running, resulting in a local denial of service. The vulnerability is not currently listed in CISA's KEV, but the presence of a kernel crash and lack of a hardening path suggest the risk is significant for impacted systems.
Debian DLA
Ubuntu USN