{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2022-50630", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-08T01:14:55.192Z", "datePublished": "2025-12-08T01:16:45.555Z", "dateUpdated": "2026-08-05T08:59:13.840Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:59:13.840Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: hugetlb: fix UAF in hugetlb_handle_userfault\n\nThe vma_lock and hugetlb_fault_mutex are dropped before handling userfault\nand reacquire them again after handle_userfault(), but reacquire the\nvma_lock could lead to UAF[1,2] due to the following race,\n\nhugetlb_fault\n hugetlb_no_page\n /*unlock vma_lock */\n hugetlb_handle_userfault\n handle_userfault\n /* unlock mm->mmap_lock*/\n vm_mmap_pgoff\n do_mmap\n mmap_region\n munmap_vma_range\n /* clean old vma */\n /* lock vma_lock again <--- UAF */\n /* unlock vma_lock */\n\nSince the vma_lock will unlock immediately after\nhugetlb_handle_userfault(), let's drop the unneeded lock and unlock in\nhugetlb_handle_userfault() to fix the issue.\n\n[1] https://lore.kernel.org/linux-mm/000000000000d5e00a05e834962e@google.com/\n[2] https://lore.kernel.org/linux-mm/20220921014457.1668-1-liuzixian4@huawei.com/" } ], "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 - Exploitation requires local syscalls (MAP_HUGETLB mmap, userfaultfd register, and a page fault into hugetlb_fault→hugetlb_no_page→hugetlb_handle_userfault); it is not reachable via network packet processing.\nAC:L - The attacker controls both sides of the race—one thread sleeps in handle_userfault after mmap_lock is dropped while another thread munmaps/remaps the same range—creating a large, attacker-driven window to free the VMA/inode before the pointless re-lock.\nPR:L - An unprivileged user can open userfaultfd with UFFD_USER_MODE_ONLY (always allowed) and create hugetlb mappings via MAP_HUGETLB (HUGETLB_ANONHUGE_INODE bypasses the CAP_IPC_LOCK/shm_group check used only for SHM_HUGETLB).\nUI:N - The attacker triggers the fault and concurrent munmap/remap entirely within their own process; no victim action is required.\nS:U - This is a standard in-kernel memory-management UAF that affects the same host kernel privilege boundary, not a VM escape or cross-authority boundary crossing.\nC:H - The UAF is on a freed hugetlbfs_inode slab object (RCU-delayed free), which can be reclaimed and controlled to obtain an arbitrary kernel read primitive.\nI:H - A controllable slab UAF on the hugetlbfs inode enables heap spraying and an arbitrary write / control-flow hijack primitive for privilege escalation.\nA:H - The demonstrated KASAN use-after-free read causes a kernel oops/crash, and any failed exploit attempt can panic or hang the system." } ] } ], "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": "1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45", "lessThan": "45c33966759ea1b4040c08dacda99ef623c0ca29", "status": "affected", "versionType": "git" }, { "version": "1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45", "lessThan": "0db2efb3bff879566f05341d94c3de00ac95c4cc", "status": "affected", "versionType": "git" }, { "version": "1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45", "lessThan": "dd691973f67b2800a97db723b1ff6f07fdcf7f5a", "status": "affected", "versionType": "git" }, { "version": "1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45", "lessThan": "78504bcedb2f1bbfb353b4d233c24d641c4dda33", "status": "affected", "versionType": "git" }, { "version": "1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45", "lessThan": "958f32ce832ba781ac20e11bb2d12a9352ea28fc", "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": "4.11", "status": "affected" }, { "version": "0", "lessThan": "4.11", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.150", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.75", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.19.17", "lessThanOrEqual": "5.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.0.3", "lessThanOrEqual": "6.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1", "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": "4.11", "versionEndExcluding": "5.10.150" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "5.15.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "5.19.17" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "6.0.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "6.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/45c33966759ea1b4040c08dacda99ef623c0ca29" }, { "url": "https://git.kernel.org/stable/c/0db2efb3bff879566f05341d94c3de00ac95c4cc" }, { "url": "https://git.kernel.org/stable/c/dd691973f67b2800a97db723b1ff6f07fdcf7f5a" }, { "url": "https://git.kernel.org/stable/c/78504bcedb2f1bbfb353b4d233c24d641c4dda33" }, { "url": "https://git.kernel.org/stable/c/958f32ce832ba781ac20e11bb2d12a9352ea28fc" } ], "title": "mm: hugetlb: fix UAF in hugetlb_handle_userfault", "x_generator": { "engine": "bippy-1.2.0" } } } }