CVE-2026-23085

Summary

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 Software

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://git.kernel.org/stable/c/e332b3b69e5b3acf07204a4b185071bab15c2b88
• https://git.kernel.org/stable/c/e2f9c751f73a2d5bb62d94ab030aec118a811f27
• https://git.kernel.org/stable/c/85215d633983233809f7d4dad163b953331b8238
• https://git.kernel.org/stable/c/1b323391560354d8c515de8658b057a1daa82adb
• https://git.kernel.org/stable/c/084ba3b99f2dfd991ce7e84fb17117319ec3cd9f
• https://git.kernel.org/stable/c/03faa61eb4b9ca9aa09bd91d4c3773d8e7b1ac98
• https://git.kernel.org/stable/c/8d76a7d89c12d08382b66e2f21f20d0627d14859

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