{"id":"CVE-2022-50630","state":"PUBLISHED","title":"mm: hugetlb: fix UAF in hugetlb_handle_userfault","description":"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/","publishedAt":"2025-12-08T01:16:45.555Z","updatedAt":"2026-10-15T21:41:21.996Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"45c33966759ea1b4040c08dacda99ef623c0ca29","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"0db2efb3bff879566f05341d94c3de00ac95c4cc","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"dd691973f67b2800a97db723b1ff6f07fdcf7f5a","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"78504bcedb2f1bbfb353b4d233c24d641c4dda33","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"958f32ce832ba781ac20e11bb2d12a9352ea28fc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"5.10.150","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.75","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.19.17","status":"unaffected","lessThanOrEqual":"5.19.*","versionType":"semver"},{"version":"6.0.3","status":"unaffected","lessThanOrEqual":"6.0.*","versionType":"semver"},{"version":"6.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]}],"references":["https://git.kernel.org/stable/c/45c33966759ea1b4040c08dacda99ef623c0ca29","https://git.kernel.org/stable/c/0db2efb3bff879566f05341d94c3de00ac95c4cc","https://git.kernel.org/stable/c/dd691973f67b2800a97db723b1ff6f07fdcf7f5a","https://git.kernel.org/stable/c/78504bcedb2f1bbfb353b4d233c24d641c4dda33","https://git.kernel.org/stable/c/958f32ce832ba781ac20e11bb2d12a9352ea28fc"],"weaknesses":[],"ingestedAt":"2026-10-29T20:05:26.763Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/50xxx/CVE-2022-50630.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-50630","state":"PUBLISHED","datePublished":"2025-12-08T01:16:45.555Z","dateUpdated":"2026-10-15T21:41:21.996Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-12-08T01:14:55.192Z"},"containers":{"cna":{"title":"mm: hugetlb: fix UAF in hugetlb_handle_userfault","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/"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"45c33966759ea1b4040c08dacda99ef623c0ca29","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"0db2efb3bff879566f05341d94c3de00ac95c4cc","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"dd691973f67b2800a97db723b1ff6f07fdcf7f5a","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"78504bcedb2f1bbfb353b4d233c24d641c4dda33","versionType":"git"},{"version":"1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45","status":"affected","lessThan":"958f32ce832ba781ac20e11bb2d12a9352ea28fc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"5.10.150","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.75","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.19.17","status":"unaffected","lessThanOrEqual":"5.19.*","versionType":"semver"},{"version":"6.0.3","status":"unaffected","lessThanOrEqual":"6.0.*","versionType":"semver"},{"version":"6.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:59:13.840Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP 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