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CVE-2024-56760 – Linux kernel PCI/MSI MSI-RISCV Incorrect Legacy Fallback Handling Vulnerability

The following table lists the changes that have been made to the
CVE-2024-56760 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution
of a vulnerability, and for identifying the most recent changes that may
impact the vulnerability’s severity, exploitability, or other characteristics.

  • New CVE Received
    by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jan. 06, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved:

    PCI/MSI: Handle lack of irqdomain gracefully

    Alexandre observed a warning emitted from pci_msi_setup_msi_irqs() on a
    RISCV platform which does not provide PCI/MSI support:

    WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
    __pci_enable_msix_range+0x30c/0x596
    pci_msi_setup_msi_irqs+0x2c/0x32
    pci_alloc_irq_vectors_affinity+0xb8/0xe2

    RISCV uses hierarchical interrupt domains and correctly does not implement
    the legacy fallback. The warning triggers from the legacy fallback stub.

    That warning is bogus as the PCI/MSI layer knows whether a PCI/MSI parent
    domain is associated with the device or not. There is a check for MSI-X,
    which has a legacy assumption. But that legacy fallback assumption is only
    valid when legacy support is enabled, but otherwise the check should simply
    return -ENOTSUPP.

    Loongarch tripped over the same problem and blindly enabled legacy support
    without implementing the legacy fallbacks. There are weak implementations
    which return an error, so the problem was papered over.

    Correct pci_msi_domain_supports() to evaluate the legacy mode and add
    the missing supported check into the MSI enable path to complete it.
    Added Reference https://git.kernel.org/stable/c/a60b990798eb17433d0283788280422b1bd94b18
    Added Reference https://git.kernel.org/stable/c/aed157301c659a48f5564cc4568cf0e5c8831af0
    Added Reference https://git.kernel.org/stable/c/b1f7476e07b93d65a1a3643dcb4a7bed80d4328d
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