In the Linux kernel, the following vulnerability has been resolved: iommupt: Check for missing PAGE_SIZE in the pgsize_bitmap Sashiko pointed out that the driver could drop PAGE_SIZE from the pgsize_bitmap. That is technically allowed but nothing does it, and such an iommu_domain would not be used with the DMA API today. Still, it is against the design and it is trivial to fix up. Lift the PT_WARN_ON to the if branch and just skip the fast path.
https://git.kernel.org/stable/c/8ef3f77c440005c7f04229a75976bfc078364247
https://git.kernel.org/stable/c/00850f41da24423587abd6124a790dd4f12bcef3