CVE-2024-56668 iommu/vt-d: Fix qi_batch NULL pointer with nested parent domain
A missing allocation in the Linux kernel IOMMU driver causes a NULL pointer dereference, leading to a system crash when mapping pages for nested parent domains.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-56668?
CVE-2024-56668 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Fix qi_batch NULL pointer with nested parent domain
The qi_batch is allocated when assigning cache tag for a domain. While for nested parent domain, it is missed. Hence, when trying to map pages to the nested parent, NULL dereference occurred. Also, there is potential memleak since there is no lock around domain->qi_batch allocation.
To solve it, add a helper for qi_batch allocation, and call it in both the __cache_tag_assign_domain() and __cache_tag_assign_parent_domain().
BUG: kernel NULL pointer dereference, address: 0000000000000200 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 8104795067 P4D 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 223 UID: 0 PID: 4357 Comm: qemu-system-x86 Not tainted 6.13.0-rc1-00028-g4b50c3c3b998-dirty #2632 Call Trace: ? __die+0x24/0x70 ? page_fault_oops+0x80/0x150 ? do_user_addr_fault+0x63/0x7b0 ? exc_page_fault+0x7c/0x220 ? asm_exc_page_fault+0x26/0x30 ? cache_tag_flush_range_np+0x13c/0x260 intel_iommu_iotlb_sync_map+0x1a/0x30 iommu_map+0x61/0xf0 batch_to_domain+0x188/0x250 iopt_area_fill_domains+0x125/0x320 ? rcu_is_watching+0x11/0x50 iopt_map_pages+0x63/0x100 iopt_map_common.isra.0+0xa7/0x190 iopt_map_user_pages+0x6a/0x80 iommufd_ioas_map+0xcd/0x1d0 iommufd_fops_ioctl+0x118/0x1c0 __x64_sys_ioctl+0x93/0xc0 do_syscall_64+0x71/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Which versions are affected by CVE-2024-56668?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-56668?
Apply the vendor's patch.
Is CVE-2024-56668 being exploited?
There is no known exploitation of CVE-2024-56668 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-56668, DEBIAN-CVE-2024-56668, GHSA-7hpx-3fcf-fxr2, UBUNTU-CVE-2024-56668.