{"id":"CVE-2026-53283","title":"iommu/amd: Bounds-check devid in __rlookup_amd_iommu()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Bounds-check devid in __rlookup_amd_iommu()\n\niommu_device_register() walks every device on the PCI bus via\nbus_for_each_dev() and calls amd_iommu_probe_devic…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= e874c666b15bcb6280c4e747d8de3879bb728829 < f0a0f01787ecece814414b0665df879b69849d09","Linux >= e874c666b15bcb6280c4e747d8de3879bb728829 < 79db4cbab81f07ce69a93d379ebd40d3709ecfb2","Linux >= e874c666b15bcb6280c4e747d8de3879bb728829 < 07d0f496fe7ec5abe3bee7e38be709521567bb33","Linux 6.16"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:25:02.512373Z"},"published":"2026-06-26","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:34:17.582Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-53283","references":[{"url":"https://git.kernel.org/stable/c/f0a0f01787ecece814414b0665df879b69849d09"},{"url":"https://git.kernel.org/stable/c/79db4cbab81f07ce69a93d379ebd40d3709ecfb2"},{"url":"https://git.kernel.org/stable/c/07d0f496fe7ec5abe3bee7e38be709521567bb33"}],"tags":["cve.org"],"epss":0.0016,"epssPercentile":0.0521,"ingestedAt":"2026-11-06T16:57:43.257Z","slug":"CVE-2026-53283","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Bounds-check devid in __rlookup_amd_iommu()\n\niommu_device_register() walks every device on the PCI bus via\nbus_for_each_dev() and calls amd_iommu_probe_device() for each. The\ninlined check_device() path computes the device's sbdf, calls\nrlookup_amd_iommu() to find the owning IOMMU, and only afterwards\nverifies devid <= pci_seg->last_bdf. __rlookup_amd_iommu() indexes\nrlookup_table[devid] with no bounds check of its own, so for a PCI\ndevice whose BDF is not described by the IVRS, the lookup reads past\nthe end of the allocation before the caller's bounds check can run.\n\nThis was harmless before commit e874c666b15b (\"iommu/amd: Change\nrlookup, irq_lookup, and alias to use kvalloc()\"): the table was a\nzeroed page-order allocation, so the over-read returned NULL and the\ncaller's NULL check skipped the device. After that commit the table is\na tight kvcalloc() and the over-read returns adjacent slab contents,\nwhich check_device() then dereferences as a struct amd_iommu *,\ncausing a boot-time GPF.\n\nSeen on Google Compute Engine ct6e VMs, where the virtualized IVRS\ndescribes only the four TPU endpoints 00:04.0-07.0; the gVNIC at\n00:08.0 (devid 0x40) indexes 56 bytes past the 456-byte allocation,\ninto the adjacent kmalloc-512 slab object:\n\n  pci 0000:00:04.0: Adding to iommu group 0\n  pci 0000:00:05.0: Adding to iommu group 1\n  pci 0000:00:06.0: Adding to iommu group 2\n  pci 0000:00:07.0: Adding to iommu group 3\n  Oops: general protection fault, probably for non-canonical address 0x3a64695f78746382: 0000 [#1] SMP NOPTI\n  CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.22 #1\n  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/06/2025\n  RIP: 0010:amd_iommu_probe_device+0x54/0x3a0\n  Call Trace:\n   __iommu_probe_device+0x107/0x520\n   probe_iommu_group+0x29/0x50\n   bus_for_each_dev+0x7e/0xe0\n   iommu_device_register+0xc9/0x240\n   iommu_go_to_state+0x9c0/0x1c60\n   amd_iommu_init+0x14/0x40\n   pci_iommu_init+0x16/0x60\n   do_one_initcall+0x47/0x2f0\n\nGuard the array access in __rlookup_amd_iommu(). With the fix applied\non 6.18.22, the gVNIC at 00:08.0 is skipped cleanly and the VM boots.\n\n## Affected\n\n- `Linux >= e874c666b15bcb6280c4e747d8de3879bb728829 < f0a0f01787ecece814414b0665df879b69849d09`\n- `Linux >= e874c666b15bcb6280c4e747d8de3879bb728829 < 79db4cbab81f07ce69a93d379ebd40d3709ecfb2`\n- `Linux >= e874c666b15bcb6280c4e747d8de3879bb728829 < 07d0f496fe7ec5abe3bee7e38be709521567bb33`\n- `Linux 6.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}