{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74518", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.910Z", "datePublished": "2026-08-15T12:27:37.480Z", "dateUpdated": "2026-08-19T16:38:19.402Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:38:19.402Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix list corruption in allocate_file_region_entries()\n\nallocate_file_region_entries() tops up resv->region_cache with freshly\nallocated file_region descriptors. The allocation uses GFP_KERNEL, so\nresv->lock is dropped around it: the new entries are gathered on a\nstack-local list head, allocated_regions, and spliced into\nresv->region_cache once the lock is re-acquired.\n\nThe splice used list_splice(), which moves the entries but does not\nre-initialize the source head, so allocated_regions is left pointing at an\nentry that now lives on resv->region_cache. The top-up runs in a while\nloop that re-checks the cache deficit after re-acquiring the lock. For a\nshared mapping the resv_map is shared by every mapper of the hugetlbfs\ninode, so a concurrent region_chg()/region_add()/region_del() on the same\nresv_map can consume cache entries during the unlocked window and force a\nsecond iteration. That iteration calls list_add() on the stale head and\ncorrupts the list; with CONFIG_DEBUG_LIST the __list_add_valid() check\ntrips:\n\n list_add corruption. next->prev should be prev (ffffc900011ff7f8),\n but was ffff88814c281460. (next=ffff88814c545640).\n kernel BUG at lib/list_debug.c:31!\n allocate_file_region_entries+0x191/0x420\n region_chg+0x267/0x300\n hugetlb_reserve_pages+0x387/0xc80\n hugetlbfs_file_mmap+0x2ce/0x3f0\n mmap_region+0x1348/0x1a80\n do_mmap+0x85e/0xb90\n vm_mmap_pgoff+0x18c/0x330\n ksys_mmap_pgoff+0x2a1/0x3e0\n do_syscall_64+0xd7/0x420\n\nWithout CONFIG_DEBUG_LIST the bad list_add() silently links a kernel-stack\naddress into resv->region_cache, leading to later use-after-free.\n\nThis was observed as a real host panic on a dense KVM host where a QEMU\nguest-RAM hugetlbfs file was mapped MAP_SHARED by both QEMU and a separate\nSPDK/DPDK vhost-user target, generating concurrent region_* traffic on one\nshared resv_map.\n\nUse list_splice_init() so the source head is re-initialized empty after\neach splice, making the retry loop safe." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only through local hugetlb reservation paths (mmap/memfd_create/fault syscalls into region_chg/region_add/region_del); no network protocol or remote packet handler invokes allocate_file_region_entries().\nAC:L - Exploitation needs a race while resv->lock is dropped during GFP_KERNEL allocation, but an attacker can spawn concurrent MAP_SHARED mappers/faulters on one hugetlb inode and controls both sides of that race.\nPR:L - Unprivileged local users can trigger this via memfd_create(MFD_HUGETLB) plus MAP_SHARED mmap/fault activity, or by mapping accessible shared hugetlbfs files, without init-namespace root or special capabilities.\nUI:N - No victim interaction is required; the attacker drives the needed concurrent syscalls and shared hugetlb mappings themselves to hit the corrupted list splice retry path.\nS:U - Impact is kernel hugetlb resv_map list/memory corruption on the host; it does not by itself cross a VM, IOMMU, or separate security-authority boundary even though KVM/DPDK hosts are a prime deployment.\nC:H - Without CONFIG_DEBUG_LIST, stale list_splice leaves a kernel-stack pointer in resv->region_cache, producing later use-after-free that can be turned into arbitrary kernel memory read/disclosure primitives.\nI:H - Corrupted region_cache pointers let subsequent region_add/region_del/cache operations write through attacker-influenced list links, enabling heap metadata corruption and potential arbitrary kernel write or code execution.\nA:H - Real host panics were reported on dense KVM hugetlb workloads; DEBUG_LIST kernels BUG on list_add corruption, and default builds can crash from UAF while walking the poisoned region_cache." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "mm/hugetlb.c" ], "versions": [ { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "01b8569233e47693d6ff7efa96d9854c55f936fc", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "9c5fdffc5e1ce84403c58289ee72697051803bf7", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "62e1c2741a4d923d9854efd5927a6212aad7a187", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "587a0accc2b4fccc5cf7baf0fe34e50efde51f9c", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "ac1bb7fd45088d0db57a22ce7729f258ebd63cf5", "status": "affected", "versionType": "git" }, { "version": "d3ec7b6e09e512ba902b86bcca2c512fb06d492f", "lessThan": "dd9623f58ec702a07b2d67179d6fcea79c52231a", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "mm/hugetlb.c" ], "versions": [ { "version": "5.10", "status": "affected" }, { "version": "0", "lessThan": "5.10", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.6.151" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.12.103" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.18.44" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "7.1.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/01b8569233e47693d6ff7efa96d9854c55f936fc" }, { "url": "https://git.kernel.org/stable/c/9c5fdffc5e1ce84403c58289ee72697051803bf7" }, { "url": "https://git.kernel.org/stable/c/f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3" }, { "url": "https://git.kernel.org/stable/c/62e1c2741a4d923d9854efd5927a6212aad7a187" }, { "url": "https://git.kernel.org/stable/c/587a0accc2b4fccc5cf7baf0fe34e50efde51f9c" }, { "url": "https://git.kernel.org/stable/c/126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df" }, { "url": "https://git.kernel.org/stable/c/ac1bb7fd45088d0db57a22ce7729f258ebd63cf5" }, { "url": "https://git.kernel.org/stable/c/dd9623f58ec702a07b2d67179d6fcea79c52231a" } ], "title": "mm/hugetlb: fix list corruption in allocate_file_region_entries()", "x_generator": { "engine": "bippy-1.2.0" } } } }