CVE-2025-21984

{"id": "CVE-2025-21984", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 4.7, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.0}]}, "published": "2025-04-01T16:15:29.810", "references": [{"url": "https://git.kernel.org/stable/c/4e9507246298fd6f1ca7bb42ef01a6e34fb93684", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b1e11bd86c0943bb7624efebdc384340a50ad683", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/c50f8e6053b0503375c2975bf47f182445aebb4c", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-362"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix kernel BUG when userfaultfd_move encounters swapcache\n\nuserfaultfd_move() checks whether the PTE entry is present or a\nswap entry.\n\n- If the PTE entry is present, move_present_pte() handles folio\n migration by setting:\n\n src_folio->index = linear_page_index(dst_vma, dst_addr);\n\n- If the PTE entry is a swap entry, move_swap_pte() simply copies\n the PTE to the new dst_addr.\n\nThis approach is incorrect because, even if the PTE is a swap entry,\nit can still reference a folio that remains in the swap cache.\n\nThis creates a race window between steps 2 and 4.\n 1. add_to_swap: The folio is added to the swapcache.\n 2. try_to_unmap: PTEs are converted to swap entries.\n 3. pageout: The folio is written back.\n 4. Swapcache is cleared.\nIf userfaultfd_move() occurs in the window between steps 2 and 4,\nafter the swap PTE has been moved to the destination, accessing the\ndestination triggers do_swap_page(), which may locate the folio in\nthe swapcache. However, since the folio's index has not been updated\nto match the destination VMA, do_swap_page() will detect a mismatch.\n\nThis can result in two critical issues depending on the system\nconfiguration.\n\nIf KSM is disabled, both small and large folios can trigger a BUG\nduring the add_rmap operation due to:\n\n page_pgoff(folio, page) != linear_page_index(vma, address)\n\n[ 13.336953] page: refcount:6 mapcount:1 mapping:00000000f43db19c index:0xffffaf150 pfn:0x4667c\n[ 13.337520] head: order:2 mapcount:1 entire_mapcount:0 nr_pages_mapped:1 pincount:0\n[ 13.337716] memcg:ffff00000405f000\n[ 13.337849] anon flags: 0x3fffc0000020459(locked|uptodate|dirty|owner_priv_1|head|swapbacked|node=0|zone=0|lastcpupid=0xffff)\n[ 13.338630] raw: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361\n[ 13.338831] raw: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000\n[ 13.339031] head: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361\n[ 13.339204] head: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000\n[ 13.339375] head: 03fffc0000000202 fffffdffc0199f01 ffffffff00000000 0000000000000001\n[ 13.339546] head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000\n[ 13.339736] page dumped because: VM_BUG_ON_PAGE(page_pgoff(folio, page) != linear_page_index(vma, address))\n[ 13.340190] ------------[ cut here ]------------\n[ 13.340316] kernel BUG at mm/rmap.c:1380!\n[ 13.340683] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP\n[ 13.340969] Modules linked in:\n[ 13.341257] CPU: 1 UID: 0 PID: 107 Comm: a.out Not tainted 6.14.0-rc3-gcf42737e247a-dirty #299\n[ 13.341470] Hardware name: linux,dummy-virt (DT)\n[ 13.341671] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n[ 13.341815] pc : __page_check_anon_rmap+0xa0/0xb0\n[ 13.341920] lr : __page_check_anon_rmap+0xa0/0xb0\n[ 13.342018] sp : ffff80008752bb20\n[ 13.342093] x29: ffff80008752bb20 x28: fffffdffc0199f00 x27: 0000000000000001\n[ 13.342404] x26: 0000000000000000 x25: 0000000000000001 x24: 0000000000000001\n[ 13.342575] x23: 0000ffffaf0d0000 x22: 0000ffffaf0d0000 x21: fffffdffc0199f00\n[ 13.342731] x20: fffffdffc0199f00 x19: ffff000006210700 x18: 00000000ffffffff\n[ 13.342881] x17: 6c203d2120296567 x16: 6170202c6f696c6f x15: 662866666f67705f\n[ 13.343033] x14: 6567617028454741 x13: 2929737365726464 x12: ffff800083728ab0\n[ 13.343183] x11: ffff800082996bf8 x10: 0000000000000fd7 x9 : ffff80008011bc40\n[ 13.343351] x8 : 0000000000017fe8 x7 : 00000000fffff000 x6 : ffff8000829eebf8\n[ 13.343498] x5 : c0000000fffff000 x4 : 0000000000000000 x3 : 0000000000000000\n[ 13.343645] x2 : 0000000000000000 x1 : ffff0000062db980 x0 : 000000000000005f\n[ 13.343876] Call trace:\n[ 13.344045] __page_check_anon_rmap+0xa0/0xb0 (P)\n[ 13.344234] folio_add_anon_rmap_ptes+0x22c/0x320\n[ 13.344333] do_swap_page+0x1060/0x1400\n[ 13.344417] __handl\n---truncated---"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm: se corrige el ERROR del kernel cuando userfaultfd_move encuentra swapcache userfaultfd_move() comprueba si la entrada PTE est\u00e1 presente o es una entrada de intercambio. - Si la entrada PTE est\u00e1 presente, move_present_pte() maneja la migraci\u00f3n de folio mediante la configuraci\u00f3n: src_folio->index = linear_page_index(dst_vma, dst_addr); - Si la entrada PTE es una entrada de intercambio, move_swap_pte() simplemente copia el PTE al nuevo dst_addr. Este enfoque es incorrecto porque, incluso si el PTE es una entrada de intercambio, a\u00fan puede hacer referencia a un folio que permanece en el cach\u00e9 de intercambio. Esto crea una ventana de ejecuci\u00f3n entre los pasos 2 y 4. 1. add_to_swap: el folio se agrega al cach\u00e9 de intercambio. 2. try_to_unmap: los PTE se convierten en entradas de intercambio. 3. pageout: el folio se vuelve a escribir. 4. Se borra la cach\u00e9 de intercambio. Si se produce userfaultfd_move() en la ventana entre los pasos 2 y 4, despu\u00e9s de mover el PTE de intercambio a su destino, al acceder a este se activa do_swap_page(), que puede localizar el folio en la cach\u00e9 de intercambio. Sin embargo, dado que el \u00edndice del folio no se ha actualizado para que coincida con el VMA de destino, do_swap_page() detectar\u00e1 una discrepancia. Esto puede provocar dos problemas cr\u00edticos seg\u00fan la configuraci\u00f3n del sistema. Si KSM est\u00e1 deshabilitado, tanto los folios peque\u00f1os como los grandes pueden generar un ERROR durante la operaci\u00f3n add_rmap debido a: page_pgoff(folio, page) != linear_page_index(vma, address) [ 13.336953] page: refcount:6 mapcount:1 mapping:00000000f43db19c index:0xffffaf150 pfn:0x4667c [ 13.337520] head: order:2 mapcount:1 entire_mapcount:0 nr_pages_mapped:1 pincount:0 [ 13.337716] memcg:ffff00000405f000 [ 13.337849] anon flags: 0x3fffc0000020459(bloqueado|actualizado|sucio|propietario_priv_1|cabezal|swapbacked|nodo=0|zona=0|lastcpupid=0xffff) [13.338630] sin procesar: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361 [13.338831] sin procesar: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000 [13.339031] cabezal: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361 [ 13.339204] cabeza: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000 [ 13.339375] cabeza: 03fffc0000000202 fffffdffc0199f01 ffffffff00000000 0000000000000001 [ 13.339546] cabeza: 000000000000004 0000000000000000 00000000ffffffff 0000000000000000 [ 13.339736] p\u00e1gina volcada porque: VM_BUG_ON_PAGE(page_pgoff(folio, page) != linear_page_index(vma, address)) [ 13.340190] ------------[ cortar aqu\u00ed ]------------ [ 13.340316] \u00a1ERROR del kernel en mm/rmap.c:1380! [ 13.340683] Error interno: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP [ 13.340969] M\u00f3dulos vinculados: [ 13.341257] CPU: 1 UID: 0 PID: 107 Comm: a.out No contaminado 6.14.0-rc3-gcf42737e247a-dirty #299 [ 13.341470] Nombre del hardware: linux,dummy-virt (DT) [ 13.341671] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 13.341815] pc : __page_check_anon_rmap+0xa0/0xb0 [ 13.341920] lr : __page_check_anon_rmap+0xa0/0xb0 [ 13.342018] sp : ffff80008752bb20 [ 13.342093] x29: ffff80008752bb20 x28: fffffdffc0199f00 x27: 0000000000000001 [ 13.342404] x26: 0000000000000000 x25: 0000000000000001 x24: 0000000000000001 [ 13.342575] x23: 0000ffffaf0d0000 x22: 0000ffffaf0d0000 x21: fffffdffc0199f00 [ 13.342731] x20: fffffdffc0199f00 x19: ffff000006210700 x18: 00000000ffffffff [ 13.342881] x17: 6c203d2120296567 x16: 6170202c6f696c6f x15: 662866666f67705f [ 13.343033] x14: 6567617028454741 x13: 2929737365726464 x12: ffff800083728ab0 [ 13.343183] x11: ffff800082996bf8 x10: 0000000000000fd7 x9: ffff80008011bc40 [ 13.343351] x8: 0000000000017fe8 x7: 00000000fffff000 x6: ffff8000829eebf8 [ 13.343498] x5: c0000000fffff000 x4: 0000000000000000 x3: 0000000000000000 [ 13.343645] x2: 0000000000000000 x1 : ffff0000062db980 x0 : 000000000000005f [ 13.343876] Rastreo de llamadas: [ 13.344045] __page_check_anon_rmap+0xa0/0xb0 ---truncado---"}], "lastModified": "2025-04-10T13:25:15.120", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "AD00A08B-A8BF-407B-95F5-DCADBFF79F01", "versionEndExcluding": "6.12.20", "versionStartIncluding": "6.8"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0A20D4D7-B329-4C68-B662-76062EA7DCF0", "versionEndExcluding": "6.13.8", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "66619FB8-0AAF-4166-B2CF-67B24143261D"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "D3D6550E-6679-4560-902D-AF52DCFE905B"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "45B90F6B-BEC7-4D4E-883A-9DBADE021750"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}