CVE-2026-23085: irqchip/gic-v3-its: Avoid truncating memory addresses

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-04 · updated 2026-10-19
Weakness: CWE-190

Description

In the Linux kernel, the following vulnerability has been resolved: irqchip/gic-v3-its: Avoid truncating memory addresses On 32-bit machines with CONFIG_ARM_LPAE, it is possible for lowmem allocations to be backed by addresses physical memory above the 32-bit address limit, as found while experimenting with larger VMSPLIT configurations. This caused the qemu virt model to crash in the GICv3 driver, which allocates the 'itt' object using GFP_KERNEL. Since all memory below the 4GB physical address limit is in ZONE_DMA in this configuration, kmalloc() defaults to higher addresses for ZONE_NORMAL, and the ITS driver stores the physical address in a 32-bit 'unsigned long' variable. Change the itt_addr variable to the correct phys_addr_t type instead, along with all other variables in this driver that hold a physical address. The gicv5 driver correctly uses u64 variables, while all other irqchip drivers don't call virt_to_phys or similar interfaces. It's expected that other device drivers have similar issues, but fixing this one is sufficient for booting a virtio based guest.

Affected products

Linux kernel: from 3.19 before 5.10.249; from 5.11 before 5.15.199; from 5.16 before 6.1.162; from 6.2 before 6.6.122; from 6.7 before 6.12.68; from 6.13 before 6.18.8 — fixed in 5.10.249, 5.15.199, 6.1.162, 6.12.68, 6.18.8, 6.6.122

How to fix

Upgrade to a fixed version: Linux kernel 5.10.249, 5.15.199, 6.1.162, 6.12.68. Check the vendor advisory for mitigations.

References

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