CVE-2024-35957

In the Linux kernel, the following vulnerability has been resolved:

iommu/vt-d: Fix WARN_ON in iommu probe path

Commit 1a75cc710b95 (iommu/vt-d: Use rbtree to track iommu probed devices) adds all devices probed by the iommu driver in a rbtree indexed by the source ID of each device. It assumes that each device has a unique source ID. This assumption is incorrect and the VT-d spec doesnt state this requirement either.

The reason for using a rbtree to track devices is to look up the device with PCI bus and devfunc in the paths of handling ATS invalidation time out error and the PRI I/O page faults. Both are PCI ATS feature related.

Only track the devices that have PCI ATS capabilities in the rbtree to avoid unnecessary WARN_ON in the iommu probe path. Otherwise, on some platforms below kernel splat will be displayed and the iommu probe results in failure.

WARNING: CPU: 3 PID: 166 at drivers/iommu/intel/iommu.c:158 intel_iommu_probe_device+0x319/0xd90 Call Trace: ? __warn+0x7e/0x180 ? intel_iommu_probe_device+0x319/0xd90 ? report_bug+0x1f8/0x200 ? handle_bug+0x3c/0x70 ? exc_invalid_op+0x18/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? intel_iommu_probe_device+0x319/0xd90 ? debug_mutex_init+0x37/0x50 __iommu_probe_device+0xf2/0x4f0 iommu_probe_device+0x22/0x70 iommu_bus_notifier+0x1e/0x40 notifier_call_chain+0x46/0x150 blocking_notifier_call_chain+0x42/0x60 bus_notify+0x2f/0x50 device_add+0x5ed/0x7e0 platform_device_add+0xf5/0x240 mfd_add_devices+0x3f9/0x500 ? preempt_count_add+0x4c/0xa0 ? up_write+0xa2/0x1b0 ? __debugfs_create_file+0xe3/0x150 intel_lpss_probe+0x49f/0x5b0 ? pci_conf1_write+0xa3/0xf0 intel_lpss_pci_probe+0xcf/0x110 [intel_lpss_pci] pci_device_probe+0x95/0x120 really_probe+0xd9/0x370 ? __pfx___driver_attach+0x10/0x10 __driver_probe_device+0x73/0x150 driver_probe_device+0x19/0xa0 __driver_attach+0xb6/0x180 ? __pfx___driver_attach+0x10/0x10 bus_for_each_dev+0x77/0xd0 bus_add_driver+0x114/0x210 driver_register+0x5b/0x110 ? __pfx_intel_lpss_pci_driver_init+0x10/0x10 [intel_lpss_pci] do_one_initcall+0x57/0x2b0 ? kmalloc_trace+0x21e/0x280 ? do_init_module+0x1e/0x210 do_init_module+0x5f/0x210 load_module+0x1d37/0x1fc0 ? init_module_from_file+0x86/0xd0 init_module_from_file+0x86/0xd0 idempotent_init_module+0x17c/0x230 __x64_sys_finit_module+0x56/0xb0 do_syscall_64+0x6e/0x140 entry_SYSCALL_64_after_hwframe+0x71/0x79

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• https://git.kernel.org/stable/c/89436f4f54125b1297aec1f466efd8acb4ec613d
• https://git.kernel.org/stable/c/fba8ca3e6f608b92e54271fdbd3ce569361939fc
• https://git.kernel.org/stable/c/89436f4f54125b1297aec1f466efd8acb4ec613d
• https://git.kernel.org/stable/c/fba8ca3e6f608b92e54271fdbd3ce569361939fc