CVE-2021-47492

{"id": "CVE-2021-47492", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "published": "2024-05-22T09:15:11.030", "references": [{"url": "https://git.kernel.org/stable/c/5e669d8ab30ab61dec3c36e27b4711f07611e6fc", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/69a7fa5cb0de06c8956b040f19a7248c8c8308ca", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/74c42e1baacf206338b1dd6b6199ac964512b5bb", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/5e669d8ab30ab61dec3c36e27b4711f07611e6fc", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://git.kernel.org/stable/c/69a7fa5cb0de06c8956b040f19a7248c8c8308ca", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://git.kernel.org/stable/c/74c42e1baacf206338b1dd6b6199ac964512b5bb", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm, thp: bail out early in collapse_file for writeback page\n\nCurrently collapse_file does not explicitly check PG_writeback, instead,\npage_has_private and try_to_release_page are used to filter writeback\npages. This does not work for xfs with blocksize equal to or larger\nthan pagesize, because in such case xfs has no page->private.\n\nThis makes collapse_file bail out early for writeback page. Otherwise,\nxfs end_page_writeback will panic as follows.\n\n page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32\n aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:\"libtest.so\"\n flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback)\n raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8\n raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000\n page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u))\n page->mem_cgroup:ffff0000c3e9a000\n ------------[ cut here ]------------\n kernel BUG at include/linux/mm.h:1212!\n Internal error: Oops - BUG: 0 [#1] SMP\n Modules linked in:\n BUG: Bad page state in process khugepaged pfn:84ef32\n xfs(E)\n page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32\n libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ...\n CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ...\n pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)\n Call trace:\n end_page_writeback+0x1c0/0x214\n iomap_finish_page_writeback+0x13c/0x204\n iomap_finish_ioend+0xe8/0x19c\n iomap_writepage_end_bio+0x38/0x50\n bio_endio+0x168/0x1ec\n blk_update_request+0x278/0x3f0\n blk_mq_end_request+0x34/0x15c\n virtblk_request_done+0x38/0x74 [virtio_blk]\n blk_done_softirq+0xc4/0x110\n __do_softirq+0x128/0x38c\n __irq_exit_rcu+0x118/0x150\n irq_exit+0x1c/0x30\n __handle_domain_irq+0x8c/0xf0\n gic_handle_irq+0x84/0x108\n el1_irq+0xcc/0x180\n arch_cpu_idle+0x18/0x40\n default_idle_call+0x4c/0x1a0\n cpuidle_idle_call+0x168/0x1e0\n do_idle+0xb4/0x104\n cpu_startup_entry+0x30/0x9c\n secondary_start_kernel+0x104/0x180\n Code: d4210000 b0006161 910c8021 94013f4d (d4210000)\n ---[ end trace 4a88c6a074082f8c ]---\n Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm, thp: rescatar temprano en el colapso_archivo para la p\u00e1gina de reescritura. Actualmente, colapso_archivo no verifica expl\u00edcitamente PG_writeback; en su lugar, page_has_private y try_to_release_page se utilizan para filtrar las p\u00e1ginas de reescritura. Esto no funciona para xfs con un tama\u00f1o de bloque igual o mayor que el tama\u00f1o de p\u00e1gina, porque en tal caso xfs no tiene p\u00e1gina-&gt;privada. Esto hace que colapso_file salga anticipadamente de la p\u00e1gina de reescritura. De lo contrario, xfs end_page_writeback entrar\u00e1 en p\u00e1nico de la siguiente manera. p\u00e1gina:fffffe00201bcc80 refcount:0 mapcount:0 mapeo:ffff0003f88c86a8 \u00edndice:0x0 pfn:0x84ef32 aops:xfs_address_space_operaciones [xfs] ino:30000b7 nombre dentry:\"libtest.so\" banderas: 0x57fffe0000008027(bloqueado|referenciado| actualizaci\u00f3n|activo|reescritura) sin formato : 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 crudo: 0000000000000000 00000000000000000 00000000ffffffff p\u00e1gina volcada porque: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u &lt;= 127u)) page-&gt;mem_cgroup:ffff0000c3e9a000 ----------- -[ cortar aqu\u00ed ]------------ \u00a1ERROR del kernel en include/linux/mm.h:1212! Error interno: Ups - ERROR: 0 [#1] M\u00f3dulos SMP vinculados en: ERROR: Estado de p\u00e1gina incorrecto en el proceso khugepaged pfn:84ef32 xfs(E) page:fffffe00201bcc80 refcount:0 mapcount:0 mapeo:0 index:0x0 pfn:0x84ef32 libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... CPU: 25 PID: 0 Comm: swapper/25 Kdump: cargado Contaminado: ... pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) Seguimiento de llamadas: end_page_writeback+0x1c0/0x214 iomap_finish_page_writeback+0x13c/0x204 iomap_finish_ioend+0xe8/0x19c iomap_writepage_end_bio+0x38/0x50 bio_endio+0x168/0x1ec blk_update_request+0x278/0x 3f0 blk_mq_end_request+0x34/0x15c virtblk_request_done+0x38/0x74 [virtio_blk ] blk_done_softirq+0xc4/0x110 __do_softirq+0x128/0x38c __irq_exit_rcu+0x118/0x150 irq_exit+0x1c/0x30 __handle_domain_irq+0x8c/0xf0 gic_handle_irq+0x84/0x108 xcc/0x180 arch_cpu_idle+0x18/0x40 default_idle_call+0x4c/0x1a0 cpuidle_idle_call+0x168/ 0x1e0 do_idle+0xb4/0x104 cpu_startup_entry+0x30/0x9c second_start_kernel+0x104/0x180 C\u00f3digo: d4210000 b0006161 910c8021 94013f4d (d4210000) ---[ end trace 4a88c6a074082f 8c ]--- P\u00e1nico en el kernel - no se sincroniza: Ups - ERROR: excepci\u00f3n fatal en la interrupci\u00f3n"}], "lastModified": "2025-09-29T16:35:34.680", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6EF3E26D-A1EF-4DE4-B0D3-23ADF141E2C5", "versionEndExcluding": "5.10.77", "versionStartIncluding": "5.4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "2681B950-4548-4649-A9E1-4124B59FC09C", "versionEndExcluding": "5.14.16", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "E46C74C6-B76B-4C94-A6A4-FD2FFF62D644"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "60134C3A-06E4-48C1-B04F-2903732A4E56"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0460DA88-8FE1-46A2-9DDA-1F1ABA552E71"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "AF55383D-4DF2-45DC-93F7-571F4F978EAB"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "9E9481B2-8AA6-4CBD-B5D3-C10F51FF6D01"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc6:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "EBD45831-4B79-42BC-ABC0-86870F0DEA89"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc7:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "948A6B8D-1B72-4945-8680-354E53BE1C80"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}