CVE-2023-54137
Unknown Unknown - Not Provided
Information Leak in Linux vfio/type1 Due to Uninitialized Memory

Publication date: 2025-12-24

Last updated on: 2025-12-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: vfio/type1: fix cap_migration information leak Fix an information leak where an uninitialized hole in struct vfio_iommu_type1_info_cap_migration on the stack is exposed to userspace. The definition of struct vfio_iommu_type1_info_cap_migration contains a hole as shown in this pahole(1) output: struct vfio_iommu_type1_info_cap_migration { struct vfio_info_cap_header header; /* 0 8 */ __u32 flags; /* 8 4 */ /* XXX 4 bytes hole, try to pack */ __u64 pgsize_bitmap; /* 16 8 */ __u64 max_dirty_bitmap_size; /* 24 8 */ /* size: 32, cachelines: 1, members: 4 */ /* sum members: 28, holes: 1, sum holes: 4 */ /* last cacheline: 32 bytes */ }; The cap_mig variable is filled in without initializing the hole: static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu, struct vfio_info_cap *caps) { struct vfio_iommu_type1_info_cap_migration cap_mig; cap_mig.header.id = VFIO_IOMMU_TYPE1_INFO_CAP_MIGRATION; cap_mig.header.version = 1; cap_mig.flags = 0; /* support minimum pgsize */ cap_mig.pgsize_bitmap = (size_t)1 << __ffs(iommu->pgsize_bitmap); cap_mig.max_dirty_bitmap_size = DIRTY_BITMAP_SIZE_MAX; return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig)); } The structure is then copied to a temporary location on the heap. At this point it's already too late and ioctl(VFIO_IOMMU_GET_INFO) copies it to userspace later: int vfio_info_add_capability(struct vfio_info_cap *caps, struct vfio_info_cap_header *cap, size_t size) { struct vfio_info_cap_header *header; header = vfio_info_cap_add(caps, size, cap->id, cap->version); if (IS_ERR(header)) return PTR_ERR(header); memcpy(header + 1, cap + 1, size - sizeof(*header)); return 0; } This issue was found by code inspection.
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Meta Information
Published
2025-12-24
Last Modified
2025-12-24
Generated
2026-05-07
AI Q&A
2025-12-24
EPSS Evaluated
2026-05-05
NVD
CVE-2023-54137
EUVD
EUVD-2023-60308
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is an information leak in the Linux kernel's vfio/type1 driver. It occurs because a structure (vfio_iommu_type1_info_cap_migration) contains an uninitialized 4-byte hole on the stack. When this structure is copied to userspace via an ioctl call, the uninitialized memory (the hole) is exposed, potentially leaking sensitive kernel memory contents to userspace.


How can this vulnerability impact me? :

The vulnerability can lead to an information leak where uninitialized kernel memory is exposed to userspace processes. This could allow an attacker or malicious user to gain access to sensitive information from kernel memory, which might be used to further exploit the system or bypass security mechanisms.


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