جزئیات آسیب‌پذیری

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Tear down scalable-mode context on probe failure intel_pasid_setup_sm_context() walks a PCI device’s DMA aliases via pci_for_each_dma_alias() and programs a scalable-mode context entry for each RID. For a device with a dma_alias_mask, the callback is invoked once for the device’s own RID and once for each alias bit, all with the same pci_dev, so device_pasid_table_setup() runs for multiple RIDs. pci_for_each_dma_alias() stops at the first callback error. Therefore, a failure partway through the walk can leave context entries for already processed RIDs present and still pointing to the device’s PASID table. On this error path, intel_iommu_probe_device() currently jumps directly to intel_pasid_free_table(), which frees the PASID table without first tearing down those context entries. The IOMMU may then walk a present context entry whose PASID table pointer references freed memory. intel_iommu_release_device() already performs teardown before freeing the table. Apply the same ordering on the probe failure path. device_pasid_table_teardown() safely handles RIDs that were never programmed: iommu_context_addr() returns NULL when no context table has been allocated, and clearing the Present bit of an already non-present entry is a no-op. So unwind is safe for both the alias that failed and any aliases not yet reached.

• https://git.kernel.org/stable/c/25ac85a9747cd63e1d166ace7b360a2cd9479d9d
• https://git.kernel.org/stable/c/d0e978ced7429b516358bb4d41d337214768ae98
• https://git.kernel.org/stable/c/db5daf25f754cdc20c18525adb88240ece6fdee9
• https://git.kernel.org/stable/c/c509fb73a1093a15accd7d43a61645d4b520f6ac