{"id":"CVE-2022-49778","state":"PUBLISHED","title":"arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud","description":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64/mm: fix incorrect file_map_count for non-leaf pmd/pud\n\nThe page table check trigger BUG_ON() unexpectedly when collapse hugepage:\n\n ------------[ cut here ]------------\n kernel BUG at mm/page_table_check.c:82!\n Internal error: Oops - BUG: 00000000f2000800 [#1] SMP\n Dumping ftrace buffer:\n    (ftrace buffer empty)\n Modules linked in:\n CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750\n Hardware name: linux,dummy-virt (DT)\n pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n pc : page_table_check_clear.isra.0+0x258/0x3f0\n lr : page_table_check_clear.isra.0+0x240/0x3f0\n[...]\n Call trace:\n  page_table_check_clear.isra.0+0x258/0x3f0\n  __page_table_check_pmd_clear+0xbc/0x108\n  pmdp_collapse_flush+0xb0/0x160\n  collapse_huge_page+0xa08/0x1080\n  hpage_collapse_scan_pmd+0xf30/0x1590\n  khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8\n  khugepaged+0x338/0x518\n  kthread+0x278/0x2f8\n  ret_from_fork+0x10/0x20\n[...]\n\nSince pmd_user_accessible_page() doesn't check if a pmd is leaf, it\ndecrease file_map_count for a non-leaf pmd comes from collapse_huge_page().\nand so trigger BUG_ON() unexpectedly.\n\nFix this problem by using pmd_leaf() insteal of pmd_present() in\npmd_user_accessible_page(). Moreover, use pud_leaf() for\npud_user_accessible_page() too.","publishedAt":"2025-05-01T14:09:13.828Z","updatedAt":"2026-05-11T19:06:36.025Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"42b2547137f5c974bb1bfd657c869fe96b96d86f","status":"affected","lessThan":"2d458046df634088611d44fd77f45465e833ef78","versionType":"git"},{"version":"42b2547137f5c974bb1bfd657c869fe96b96d86f","status":"affected","lessThan":"5b47348fc0b18a78c96f8474cc90b7525ad1bbfe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/include/asm/pgtable.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","versionType":"semver"},{"version":"6.0.10","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":["arch/arm64/include/asm/pgtable.h"]}],"references":["https://git.kernel.org/stable/c/2d458046df634088611d44fd77f45465e833ef78","https://git.kernel.org/stable/c/5b47348fc0b18a78c96f8474cc90b7525ad1bbfe"],"weaknesses":[],"ingestedAt":"2026-10-29T20:05:26.763Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/49xxx/CVE-2022-49778.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-49778","state":"PUBLISHED","datePublished":"2025-05-01T14:09:13.828Z","dateUpdated":"2026-05-11T19:06:36.025Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:17:33.805Z"},"containers":{"cna":{"title":"arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64/mm: fix incorrect file_map_count for non-leaf pmd/pud\n\nThe page table check trigger BUG_ON() unexpectedly when collapse hugepage:\n\n ------------[ cut here ]------------\n kernel BUG at mm/page_table_check.c:82!\n Internal error: Oops - BUG: 00000000f2000800 [#1] SMP\n Dumping ftrace buffer:\n    (ftrace buffer empty)\n Modules linked in:\n CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750\n Hardware name: linux,dummy-virt (DT)\n pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n pc : page_table_check_clear.isra.0+0x258/0x3f0\n lr : page_table_check_clear.isra.0+0x240/0x3f0\n[...]\n Call trace:\n  page_table_check_clear.isra.0+0x258/0x3f0\n  __page_table_check_pmd_clear+0xbc/0x108\n  pmdp_collapse_flush+0xb0/0x160\n  collapse_huge_page+0xa08/0x1080\n  hpage_collapse_scan_pmd+0xf30/0x1590\n  khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8\n  khugepaged+0x338/0x518\n  kthread+0x278/0x2f8\n  ret_from_fork+0x10/0x20\n[...]\n\nSince pmd_user_accessible_page() doesn't check if a pmd is leaf, it\ndecrease file_map_count for a non-leaf pmd comes from collapse_huge_page().\nand so trigger BUG_ON() unexpectedly.\n\nFix this problem by using pmd_leaf() insteal of pmd_present() in\npmd_user_accessible_page(). Moreover, use pud_leaf() for\npud_user_accessible_page() too."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"42b2547137f5c974bb1bfd657c869fe96b96d86f","status":"affected","lessThan":"2d458046df634088611d44fd77f45465e833ef78","versionType":"git"},{"version":"42b2547137f5c974bb1bfd657c869fe96b96d86f","status":"affected","lessThan":"5b47348fc0b18a78c96f8474cc90b7525ad1bbfe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/include/asm/pgtable.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","versionType":"semver"},{"version":"6.0.10","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":["arch/arm64/include/asm/pgtable.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/2d458046df634088611d44fd77f45465e833ef78"},{"url":"https://git.kernel.org/stable/c/5b47348fc0b18a78c96f8474cc90b7525ad1bbfe"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T19:06:36.025Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}