GHSA-78PW-R9WG-6P38
Vulnerability from github – Published: 2025-12-24 15:30 – Updated: 2025-12-24 15:30In 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.
{
"affected": [],
"aliases": [
"CVE-2023-54137"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-24T13:16:15Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvfio/type1: fix cap_migration information leak\n\nFix an information leak where an uninitialized hole in struct\nvfio_iommu_type1_info_cap_migration on the stack is exposed to userspace.\n\nThe definition of struct vfio_iommu_type1_info_cap_migration contains a hole as\nshown in this pahole(1) output:\n\n struct vfio_iommu_type1_info_cap_migration {\n struct vfio_info_cap_header header; /* 0 8 */\n __u32 flags; /* 8 4 */\n\n /* XXX 4 bytes hole, try to pack */\n\n __u64 pgsize_bitmap; /* 16 8 */\n __u64 max_dirty_bitmap_size; /* 24 8 */\n\n /* size: 32, cachelines: 1, members: 4 */\n /* sum members: 28, holes: 1, sum holes: 4 */\n /* last cacheline: 32 bytes */\n };\n\nThe cap_mig variable is filled in without initializing the hole:\n\n static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,\n struct vfio_info_cap *caps)\n {\n struct vfio_iommu_type1_info_cap_migration cap_mig;\n\n cap_mig.header.id = VFIO_IOMMU_TYPE1_INFO_CAP_MIGRATION;\n cap_mig.header.version = 1;\n\n cap_mig.flags = 0;\n /* support minimum pgsize */\n cap_mig.pgsize_bitmap = (size_t)1 \u003c\u003c __ffs(iommu-\u003epgsize_bitmap);\n cap_mig.max_dirty_bitmap_size = DIRTY_BITMAP_SIZE_MAX;\n\n return vfio_info_add_capability(caps, \u0026cap_mig.header, sizeof(cap_mig));\n }\n\nThe structure is then copied to a temporary location on the heap. At this point\nit\u0027s already too late and ioctl(VFIO_IOMMU_GET_INFO) copies it to userspace\nlater:\n\n int vfio_info_add_capability(struct vfio_info_cap *caps,\n struct vfio_info_cap_header *cap, size_t size)\n {\n struct vfio_info_cap_header *header;\n\n header = vfio_info_cap_add(caps, size, cap-\u003eid, cap-\u003eversion);\n if (IS_ERR(header))\n return PTR_ERR(header);\n\n memcpy(header + 1, cap + 1, size - sizeof(*header));\n\n return 0;\n }\n\nThis issue was found by code inspection.",
"id": "GHSA-78pw-r9wg-6p38",
"modified": "2025-12-24T15:30:39Z",
"published": "2025-12-24T15:30:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-54137"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/13fd667db999bffb557c5de7adb3c14f1713dd51"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1b5feb8497cdb5b9962db2700814bffbc030fb4a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ad83d83dd891244de0d07678b257dc976db7c132"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cbac29a1caa49a34e131394e1f4d924a76d8b0c9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cd24e2a60af633f157d7e59c0a6dba64f131c0b1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f6f300ecc196d243c02adeb9ee0c62c677c24bfb"
}
],
"schema_version": "1.4.0",
"severity": []
}
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