CVE-2026-80822 in Linux
Summary
by MITRE • 09/04/2026
In the Linux kernel, the following vulnerability has been resolved:
mailbox: mchp-ipc-sbi: Add null check for devm_kasprintf()
Add a check to see if devm_kasprintf() is not NULL in mchp_ipc_get_cluster_aggr_irq(), returning -ENOMEM if the function failed.
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Analysis
by VulDB Data Team • 09/04/2026
The Linux kernel subsystem responsible for managing mailbox communications between processing elements, specifically within the Microchip IPC SBI driver implementation, contained a critical resource allocation oversight that has been addressed through recent patching. The vulnerability centers on the mchp_ipc_get_cluster_aggr_irq function, which is tasked with retrieving and configuring interrupt lines required for inter-processor communication clusters. During its execution, this routine invokes devm_kasprintf to dynamically allocate memory for formatting strings related to IRQ naming or configuration data. In high-load scenarios or systems under memory pressure, the kernel's dynamic memory allocator may fail to satisfy such requests, resulting in a NULL pointer return value from devm_kasprintf. Prior to the fix, the code proceeded to dereference this potentially null pointer without verification, leading to an immediate kernel panic or undefined behavior due to invalid memory access.
This specific flaw represents a classic example of improper input validation regarding internal system resources rather than external user data, yet it carries severe operational consequences for system stability and availability. When devm_kasprintf fails, the subsequent dereference triggers a null pointer dereference exception within the kernel space. This typically results in an immediate crash of the operating system, manifesting as a stack trace dump followed by a halt or reboot depending on the architecture's panic settings. For systems relying on this driver for critical inter-core communication, such instability can lead to complete service outages and data corruption if processes are abruptly terminated without proper cleanup procedures. The lack of error handling also means that resource leaks may occur in subsequent operations since the failure state is not properly propagated or managed by the caller functions.
From a classification perspective, this vulnerability aligns with CWE-476, which denotes NULL Pointer Dereference vulnerabilities where software fails to check for null pointers before using them as if they were valid memory addresses. Furthermore, it relates to CWE-252 regarding unchecked return values, as the function did not verify the success of a critical allocation operation. In terms of attack vectors and behavioral mapping under MITRE ATT&CK frameworks, this issue falls under T1499 Endpoint Denial of Service, specifically reflecting techniques that exploit resource exhaustion or logic errors to disrupt service availability. Although it is primarily an internal kernel flaw rather than directly exploitable by external attackers for remote code execution, local users with the ability to trigger high memory allocation demands could potentially induce this condition intentionally to cause a denial of service against the host system.
The remediation strategy implemented involves inserting a conditional check immediately following the call to devm_kasprintf within mchp_ipc_get_cluster_aggr_irq. If the function returns NULL, indicating an out-of-memory error, the code now explicitly returns -ENOMEM to propagate this failure up the call stack rather than proceeding with invalid data structures. This approach ensures that higher-level initialization routines can detect the allocation failure and handle it gracefully, potentially by aborting device registration or triggering appropriate fallback mechanisms. To mitigate similar risks in broader kernel development practices, developers should consistently validate all dynamic memory allocations using standard error codes like -ENOMEM before dereferencing pointers. Additionally, employing static analysis tools during code review phases can help identify such omissions early in the software development lifecycle, ensuring robustness against resource exhaustion attacks and maintaining overall system integrity under varying load conditions.