CVE-2026-98855 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
of/overlay: put property on deadprops only after changeset add succeeds
add_changeset_property() links a new property of a not-yet-live target node into the node's deadprops list before handing it to of_changeset_add_property(). If that fails, the error path frees the property but leaves the freed pointer linked in deadprops, and of_node_release() frees it a second time when the aborted overlay's node is released.
Record the changeset entry first and link the property into deadprops only on success. of_changeset_add_property() never looks at the node's property lists, so the order of the two steps is otherwise immaterial, and the error path frees a property that nothing references.
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Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel device tree overlay subsystem contains a logic flaw in the handling of property additions during dynamic configuration updates. Specifically, within the add_changeset_property function implementation, there is an incorrect ordering of operations when managing memory for properties associated with nodes that are not yet live. The vulnerability arises because the code links a new property into the node's deadprops list before successfully adding it to the changeset via of_changeset_add_property. This sequence creates a race condition-like state where the pointer remains in the data structure even if the subsequent addition operation fails due to resource constraints or other errors.
When of_changeset_add_property returns an error, the kernel enters an error handling path that frees the property memory to prevent leaks. However, because the pointer was already linked into the deadprops list prior to the failure check, this freed pointer remains dangling within that list. The device tree core maintains these lists to manage lifecycle events for nodes and their associated data structures during overlay application or removal processes. Consequently, when the aborted overlay's node is eventually released through of_node_release, the system attempts to traverse and free all entries in the deadprops list again.
This results in a double-free vulnerability where memory that has already been deallocated by the error path is freed a second time. Double-free conditions are particularly dangerous as they can lead to heap corruption, kernel panics, or potentially be exploited for arbitrary code execution depending on how quickly the allocator reuses the corrupted memory region and what data an attacker might inject into it during the window of vulnerability. The issue stems from a failure to validate the success of the changeset addition before modifying persistent node state structures that are subject to subsequent cleanup routines.
The root cause is classified under CWE-415, which describes Double Free vulnerabilities. From a tactical perspective, this flaw relates to improper resource management during error handling paths in kernel subsystems, aligning with ATT&CK techniques involving exploitation of software flaws for denial of service or privilege escalation if the heap corruption can be controlled. The vulnerability highlights the importance of strict ordering in memory allocation and linkage operations within critical system components like the device tree overlay manager.
To mitigate this risk, developers must ensure that state modifications to persistent data structures such as deadprops are conditional upon the success of dependent operations. In this specific case, the fix involves recording the changeset entry first and linking the property into the deadprops list only after confirming that of_changeset_add_property has succeeded without error. This ensures that if an operation fails, no dangling references remain in lists managed by node release functions. System administrators should apply kernel updates provided by their distribution vendors to patch this logic flaw and prevent potential stability issues or security exploits arising from heap corruption during device tree overlay operations.