CVE-2026-72212 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
mm/memory_hotplug: fix incorrect altmap passing in error path
In create_altmaps_and_memory_blocks(), when arch_add_memory() succeeds with memmap_on_memory enabled, the vmemmap pages are allocated from params.altmap. If create_memory_block_devices() subsequently fails, the error path calls arch_remove_memory() with a NULL altmap instead of params.altmap.
This is a bug that could lead to memory corruption. Since altmap is NULL, vmemmap_free() falls back to freeing the vmemmap pages into the system buddy allocator via free_pages() instead of the altmap. arch_remove_memory() then immediately destroys the physical linear mapping for this memory. This injects unowned pages into the buddy allocator, causing machine checks or memory corruption if the system later attempts to allocate and use those freed pages.
Fix this by passing params.altmap to arch_remove_memory() in the error path.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the linux kernel's memory management subsystem particularly in the memory hotplug functionality where improper handling of alternate memory mapping structures can lead to critical memory corruption issues. The flaw occurs during the dynamic memory allocation process when the system attempts to add new memory regions while simultaneously managing virtual memory mappings. The issue stems from a specific code path in the create_altmaps_and_memory_blocks function that fails to maintain proper state management during error conditions, creating a scenario where memory allocation metadata becomes inconsistent and potentially leads to system instability.
The technical implementation flaw occurs when arch_add_memory() successfully allocates vmemmap pages using params.altmap as the source for memory mapping structures. However, when create_memory_block_devices() subsequently fails, the error handling routine incorrectly calls arch_remove_memory() with a NULL altmap parameter instead of preserving the original params.altmap reference that was used for allocation. This represents a classic case of improper resource management where the system loses track of memory allocation context during failure scenarios, violating fundamental principles of memory safety and resource lifecycle management.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially cause complete system crashes or data integrity violations. When vmemmap_free() receives a NULL altmap parameter, it defaults to using the system buddy allocator through free_pages() instead of properly returning pages to their original alternate mapping structure. This creates a dangerous situation where pages that should remain under controlled allocation management are instead returned to the general system memory pool, creating potential for machine check exceptions and memory corruption. The vulnerability particularly affects systems utilizing memory hotplug capabilities where dynamic memory addition is common, making it exploitable in environments with frequent memory modifications.
The fix implemented addresses this by ensuring that params.altmap is properly passed through to arch_remove_memory() during error handling paths, maintaining consistency between allocation and deallocation operations. This approach aligns with established security practices for memory management systems and follows the principle of least privilege by ensuring proper resource ownership tracking throughout all code execution paths. The solution prevents the injection of unowned pages into the buddy allocator system while maintaining the integrity of memory mapping structures. This vulnerability demonstrates the importance of careful error handling in kernel memory management and highlights how seemingly minor state management issues can have catastrophic effects on system stability. The fix directly addresses CWE-459 which deals with incomplete cleanup, ensuring proper resource deallocation and preventing memory corruption scenarios that could be exploited for privilege escalation or denial of service attacks.
This issue specifically relates to ATT&CK technique T1068 which involves exploiting local privilege escalation through kernel vulnerabilities, as well as T1499 which covers data destruction through memory corruption. The vulnerability affects systems where memory hotplug functionality is enabled and demonstrates the critical need for robust error handling in kernel-level memory management operations. Proper implementation of this fix ensures that alternate memory mapping structures maintain their integrity throughout all allocation and deallocation scenarios, preventing the potential for unauthorized memory access patterns that could be exploited by malicious actors. The solution reinforces fundamental security principles around resource management and proper state preservation during failure conditions in critical system components.