CVE-2026-90007 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
scsi: pm8001: Use rollback index when freeing MSI-X vectors
pm8001_request_msix() unwinds previously registered handlers with free_irq() when request_irq() fails. The rollback loop uses the failing index i for every iteration instead of the already registered vector index j.
That passes the wrong IRQ/dev_id pair to free_irq() and leaves the earlier handlers installed. Use j for both pci_irq_vector() and the matching irq_vector entry in the rollback loop.
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Analysis
by VulDB Data Team • 09/17/2026
The pm8001 SCSI host adapter driver within the Linux kernel contains a logic error during the initialization of Message Signaled Interrupts, specifically MSI-X vectors. This vulnerability arises from an incorrect implementation of the cleanup routine when interrupt request registration fails. The function pm8001_request_msix is responsible for allocating and registering multiple MSI-X interrupts required by the hardware to handle I/O operations efficiently. During this process, if one specific interrupt vector fails to register via the request_irq system call, the driver must unwind or rollback any previously successful registrations to prevent resource leaks and ensure a clean state before returning an error code to the caller.
The technical flaw lies in the iteration variable used during this rollback phase. The original implementation incorrectly utilizes the index of the failing interrupt vector for all iterations of the cleanup loop rather than tracking the indices of vectors that were successfully registered up to that point. Consequently, when free_irq is invoked to release previously allocated resources, it receives an incorrect device identifier and IRQ number pair. This mismatch means that instead of freeing the specific handlers that were installed earlier in the sequence, the system attempts to free non-existent or unrelated interrupt lines while leaving the actually installed handlers active but orphaned from their proper cleanup context.
This error results in a resource leak where kernel memory associated with the interrupt handler structures is not properly released. Over time, particularly on systems utilizing this driver extensively or under conditions that trigger frequent initialization failures and retries, these leaked resources can accumulate. This accumulation contributes to increased kernel memory consumption and potential fragmentation of system resources. Furthermore, leaving handlers installed without proper cleanup can lead to undefined behavior if the hardware state changes while stale interrupt vectors remain active in the kernel's internal data structures, potentially causing stability issues or unpredictable driver behavior during subsequent initialization attempts.
From a security perspective, this vulnerability is categorized under CWE-401, which describes missing release of memory after successful allocation, and CWE-783, pertaining to improper use of unlocking mechanisms if applicable to synchronization primitives involved in the interrupt handling path. In terms of attack vectors, while primarily a stability issue rather than an exploitable security flaw for privilege escalation or remote code execution, it aligns with ATT&CK technique T1562, specifically sub-technique T1562.001 which involves Impair Defenses through Disable or Modify Tools and Security Software features via system instability or resource exhaustion. An attacker could potentially leverage repeated trigger conditions to induce denial of service by exhausting kernel memory resources over time.
To mitigate this vulnerability, the patch corrects the rollback logic by ensuring that the loop variable used for freeing interrupts corresponds strictly to the indices of vectors that were successfully registered prior to the failure point. By using the correct index j instead of the failing index i, the driver ensures that free_irq is called with accurate parameters matching the actual installed handlers. This guarantees proper resource deallocation and maintains kernel integrity during error handling paths. System administrators should ensure their Linux kernels are updated to include this fix, which resolves the improper cleanup logic in the pm8001 driver and prevents the associated memory leaks and potential stability issues arising from incorrect interrupt vector management.