⚪ Revert "PCI/MSI: Unmap MSI-X region on error" (Linux Linux)

Description

In the Linux kernel, the following vulnerability has been resolved: Revert "PCI/MSI: Unmap MSI-X region on error" This reverts commit 1a8d4c6ecb4c81261bcdf13556abd4a958eca202. Commit 1a8d4c6ecb4c ("PCI/MSI: Unmap MSI-X region on error") added an iounmap(dev->msix_base) on the error path of msix_capability_init() to release the MSI-X region when msix_setup_interrupts() fails. When msix_setup_interrupts() fails, the call chain is: msix_setup_interrupts() -> __msix_setup_interrupts() struct pci_dev *dev __free(free_msi_irqs) = __dev; ... return ret; // __free cleanup fires on error The __free(free_msi_irqs) cleanup calls pci_free_msi_irqs(), which already handles the unmap: void pci_free_msi_irqs(struct pci_dev *dev) { pci_msi_teardown_msi_irqs(dev); if (dev->msix_base) { iounmap(dev->msix_base); // already unmapped here dev->msix_base = NULL; // and set to NULL } } So dev->msix_base is unmapped and set to NULL before msix_setup_interrupts() returns to msix_capability_init(). The "goto out_unmap" introduced by commit 1a8d4c6ecb4c ("PCI/MSI: Unmap MSI-X region on error") then calls iounmap() a second time on a NULL pointer. This was reproduced on Intel Emerald Rapids (192 CPUs) while running tools/testing/selftests/kexec/test_kexec_jump.sh: WARNING: CPU#44 at iounmap+0x2a/0xe0 RIP: 0010:iounmap+0x2a/0xe0 RDI: 0000000000000000 Call Trace: msix_capability_init+0x317/0x3f0 __pci_enable_msix_range+0x21d/0x2c0 pci_alloc_irq_vectors_affinity+0xa9/0x130 nvme_setup_io_queues+0x2a8/0x420 [nvme] nvme_reset_work+0x151/0x340 [nvme] ... RDI=0 confirms iounmap() is called with NULL. Restore the original "goto out_disable" and leave the unmap to the existing __free(free_msi_irqs) cleanup.