CVE-2023-54095

powerpc/iommu: Fix notifiers being shared by PCI and VIO buses

State: Published
Severity: 7.0 High
Published: Dec 24, 2025
Updated: Oct 15, 2026
Reserved: Dec 24, 2025

Description

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

powerpc/iommu: Fix notifiers being shared by PCI and VIO buses

fail_iommu_setup() registers the fail_iommu_bus_notifier struct to both PCI and VIO buses. struct notifier_block is a linked list node, so this causes any notifiers later registered to either bus type to also be registered to the other since they share the same node.

This causes issues in (at least) the vgaarb code, which registers a notifier for PCI buses. pci_notify() ends up being called on a vio device, converted with to_pci_dev() even though it's not a PCI device, and finally makes a bad access in vga_arbiter_add_pci_device() as discovered with KASAN:

BUG: KASAN: slab-out-of-bounds in vga_arbiter_add_pci_device+0x60/0xe00 Read of size 4 at addr c000000264c26fdc by task swapper/0/1

Call Trace: dump_stack_lvl+0x1bc/0x2b8 (unreliable) print_report+0x3f4/0xc60 kasan_report+0x244/0x698 __asan_load4+0xe8/0x250 vga_arbiter_add_pci_device+0x60/0xe00 pci_notify+0x88/0x444 notifier_call_chain+0x104/0x320 blocking_notifier_call_chain+0xa0/0x140 device_add+0xac8/0x1d30 device_register+0x58/0x80 vio_register_device_node+0x9ac/0xce0 vio_bus_scan_register_devices+0xc4/0x13c __machine_initcall_pseries_vio_device_init+0x94/0xf0 do_one_initcall+0x12c/0xaa8 kernel_init_freeable+0xa48/0xba8 kernel_init+0x64/0x400 ret_from_kernel_thread+0x5c/0x64

Fix this by creating separate notifier_block structs for each bus type.

[mpe: Add #ifdef to fix CONFIG_IBMVIO=n build]

Scores

CVSS	Score	Vector	Source
3.1	7.0 High	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before dc0d107e624ca96aef6dd8722eb33ba3a6d157b0Affected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before 075a4dcdbc9a5ea793cb8ec8b78a6c0b7636fd52Affected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before 65bf8a196ba25cf65a858b5bb8de80f0aad76691Affected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before f08944e3c6962b00827de7263a9e20688e79ad84Affected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before a9ddbfed53465bc7c411231db32a488066c0c1beAffected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before f17d5efaafba3d5f02f0373f7c5f44711d676f3eAffected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before c46af58588253e5e4063bb5ddc78cd12fdf9e55dAffected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before 6670c65bf863cd0d44ca24d4c10ef6755b8d9529Affected d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before c37b6908f7b2bd24dcaaf14a180e28c9132b9c58Affected
LinuxLinux	3.6Affected before 3.6Not affected 4.14.326 through 4.14.Not affected 4.19.295 through 4.19.Not affected 5.4.257 through 5.4.Not affected 5.10.195 through 5.10.Not affected 5.15.132 through 5.15.Not affected 6.1.53 through 6.1.Not affected 6.4.16 through 6.4.Not affected 6.5.3 through 6.5.Not affected 6.6 and laterNot affected

Product

Versions

LinuxLinux

d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before dc0d107e624ca96aef6dd8722eb33ba3a6d157b0Affected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before 075a4dcdbc9a5ea793cb8ec8b78a6c0b7636fd52Affected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before 65bf8a196ba25cf65a858b5bb8de80f0aad76691Affected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before f08944e3c6962b00827de7263a9e20688e79ad84Affected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before a9ddbfed53465bc7c411231db32a488066c0c1beAffected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before f17d5efaafba3d5f02f0373f7c5f44711d676f3eAffected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before c46af58588253e5e4063bb5ddc78cd12fdf9e55dAffected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before 6670c65bf863cd0d44ca24d4c10ef6755b8d9529Affected
d6b9a81b2a45786384f5bd3516bd6ddfb4b772c6 to before c37b6908f7b2bd24dcaaf14a180e28c9132b9c58Affected

LinuxLinux

3.6Affected
before 3.6Not affected
4.14.326 through 4.14.*Not affected
4.19.295 through 4.19.*Not affected
5.4.257 through 5.4.*Not affected
5.10.195 through 5.10.*Not affected
5.15.132 through 5.15.*Not affected
6.1.53 through 6.1.*Not affected
6.4.16 through 6.4.*Not affected
6.5.3 through 6.5.*Not affected
6.6 and laterNot affected

References

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