Bug 2506811 (CVE-2026-64244)

Summary: CVE-2026-64244 kernel: drivers/base/memory: set mem->altmap after successful device registration
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's memory management. This vulnerability occurs when a memory block fails to register, but its associated memory map is not properly cleared during device removal. This can lead to a system warning and potential instability or a kernel crash, allowing a local attacker to cause a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-24 16:05:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drivers/base/memory: set mem->altmap after successful device registration

If __add_memory_block() fails at xa_store() (under memory pressure for
example), device_unregister() is called, which eventually triggers
memory_block_release() with mem->altmap still set, causing a
WARN_ON(mem->altmap).  This was triggered by modifying virtio-mem driver.

Fix this by delaying the assignment of mem->altmap until after
__add_memory_block() has succeeded.
Comment 1 Mauro Matteo Cascella 2026-07-28 11:43:41 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072453-CVE-2026-64244-2efd@gregkh/T