{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-04-17T22:23:56.113","vulnerabilities":[{"cve":{"id":"CVE-2021-47566","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","published":"2024-05-24T15:15:21.637","lastModified":"2025-09-18T15:41:41.317","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nproc/vmcore: fix clearing user buffer by properly using clear_user()\n\nTo clear a user buffer we cannot simply use memset, we have to use\nclear_user().  With a virtio-mem device that registers a vmcore_cb and\nhas some logically unplugged memory inside an added Linux memory block,\nI can easily trigger a BUG by copying the vmcore via \"cp\":\n\n  systemd[1]: Starting Kdump Vmcore Save Service...\n  kdump[420]: Kdump is using the default log level(3).\n  kdump[453]: saving to /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/\n  kdump[458]: saving vmcore-dmesg.txt to /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/\n  kdump[465]: saving vmcore-dmesg.txt complete\n  kdump[467]: saving vmcore\n  BUG: unable to handle page fault for address: 00007f2374e01000\n  #PF: supervisor write access in kernel mode\n  #PF: error_code(0x0003) - permissions violation\n  PGD 7a523067 P4D 7a523067 PUD 7a528067 PMD 7a525067 PTE 800000007048f867\n  Oops: 0003 [#1] PREEMPT SMP NOPTI\n  CPU: 0 PID: 468 Comm: cp Not tainted 5.15.0+ #6\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 04/01/2014\n  RIP: 0010:read_from_oldmem.part.0.cold+0x1d/0x86\n  Code: ff ff ff e8 05 ff fe ff e9 b9 e9 7f ff 48 89 de 48 c7 c7 38 3b 60 82 e8 f1 fe fe ff 83 fd 08 72 3c 49 8d 7d 08 4c 89 e9 89 e8 <49> c7 45 00 00 00 00 00 49 c7 44 05 f8 00 00 00 00 48 83 e7 f81\n  RSP: 0018:ffffc9000073be08 EFLAGS: 00010212\n  RAX: 0000000000001000 RBX: 00000000002fd000 RCX: 00007f2374e01000\n  RDX: 0000000000000001 RSI: 00000000ffffdfff RDI: 00007f2374e01008\n  RBP: 0000000000001000 R08: 0000000000000000 R09: ffffc9000073bc50\n  R10: ffffc9000073bc48 R11: ffffffff829461a8 R12: 000000000000f000\n  R13: 00007f2374e01000 R14: 0000000000000000 R15: ffff88807bd421e8\n  FS:  00007f2374e12140(0000) GS:ffff88807f000000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007f2374e01000 CR3: 000000007a4aa000 CR4: 0000000000350eb0\n  Call Trace:\n   read_vmcore+0x236/0x2c0\n   proc_reg_read+0x55/0xa0\n   vfs_read+0x95/0x190\n   ksys_read+0x4f/0xc0\n   do_syscall_64+0x3b/0x90\n   entry_SYSCALL_64_after_hwframe+0x44/0xae\n\nSome x86-64 CPUs have a CPU feature called \"Supervisor Mode Access\nPrevention (SMAP)\", which is used to detect wrong access from the kernel\nto user buffers like this: SMAP triggers a permissions violation on\nwrong access.  In the x86-64 variant of clear_user(), SMAP is properly\nhandled via clac()+stac().\n\nTo fix, properly use clear_user() when we're dealing with a user buffer."},{"lang":"es","value":"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: proc/vmcore: corrige el borrado del búfer del usuario usando correctamente clear_user() Para borrar un búfer de usuario no podemos simplemente usar memset, tenemos que usar clear_user(). Con un dispositivo virtio-mem que registra un vmcore_cb y tiene algo de memoria lógicamente desconectada dentro de un bloque de memoria de Linux agregado, puedo desencadenar fácilmente un ERROR copiando el vmcore a través de \"cp\": systemd[1]: Iniciando el servicio Kdump Vmcore Save. . kdump[420]: Kdump está utilizando el nivel de registro predeterminado (3). kdump[453]: guardar en /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/ kdump[458]: guardar vmcore-dmesg.txt en /sysroot/var/crash/127.0 .0.1-2021-11-11-14:59:22/ kdump[465]: guardar vmcore-dmesg.txt completo kdump[467]: guardar vmcore ERROR: no se puede manejar el error de página para la dirección: 00007f2374e01000 #PF: escritura del supervisor acceso en modo kernel #PF: error_code(0x0003) - violación de permisos PGD 7a523067 P4D 7a523067 PUD 7a528067 PMD 7a525067 PTE 800000007048f867 Ups: 0003 [#1] PREEMPT SMP NOPTI CPU: 0 PID: 468 Comm: p No contaminado 5.15.0+ # 6 Nombre del hardware: PC estándar QEMU (Q35 + ICH9, 2009), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 01/04/2014 RIP: 0010:read_from_oldmem.part.0.cold+0x1d/ 0x86 Código: ff ff ff e8 05 ff fe ff e9 b9 e9 7f ff 48 89 de 48 c7 c7 38 3b 60 82 e8 f1 fe fe ff 83 fd 08 72 3c 49 8d 7d 08 4c 89 e9 89 e8 &lt;49&gt; c7 45 00 00 00 00 00 49 C7 44 05 F8 00 00 00 00 48 83 E7 F81 RSP: 0018: FFFFFC9000073BE08 EFLAGS: 00010212 RAX: 00000000000000001000 RBX: 000000002FD000 RCX: 00007F2374E RSI: 000000000000FFFFDFFF RDI: 00007F2374E01008 RBP: 000000000000001000 R08: 0000000000000000 R09: ffffc9000073bc50 R10: ffffc9000073bc48 R11: ffffffff829461a8 R12: 000000000000f000 R13: 00007f2374e01000 R14: 0000000000000000 R15: 88807bd421e8 FS: 00007f2374e12140(0000) GS:ffff88807f000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2 : 00007f2374e01000 CR3: 000000007a4aa000 CR4: 0000000000350eb0 Seguimiento de llamadas: read_vmcore+0x236/0x2c0 proc_reg_read+0x55/0xa0 vfs_read+0x95/0x190 do_syscall_64+0x3b/0x90 Entry_SYSCALL_64_after_hwframe+0x44/0xae Algunas CPU x86-64 tienen una función de CPU llamada \"Prevención de acceso en modo supervisor (SMAP)\", que se utiliza para detectar accesos incorrectos desde el kernel a los búferes de usuario como este: SMAP desencadena una violación de permisos en caso de acceso incorrecto. En la variante x86-64 de clear_user(), SMAP se maneja correctamente mediante clac()+stac(). Para solucionarlo, utilice correctamente clear_user() cuando estemos tratando con un búfer de usuario."}],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"weaknesses":[{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"CWE-787"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"4.4.294","matchCriteriaId":"B35C423A-CD8B-48D2-8C0F-200B888B53F3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"4.9.292","matchCriteriaId":"DB7F6C04-42D3-48A3-892D-2487383B9B6E"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"4.14.257","matchCriteriaId":"7080D941-9847-42F5-BA50-0A03CFB61FD1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"4.19.219","matchCriteriaId":"B9EF0575-6BF6-4AD9-B9A0-5C8D7D71710C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.4.163","matchCriteriaId":"80E8F086-C9B9-4987-8B2E-B4A16D1DA7BA"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.83","matchCriteriaId":"D4843826-EA9A-472B-82EC-B9E4FD4149AD"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.6","matchCriteriaId":"990C08FB-0121-4296-896F-556312F8FF3B"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*","matchCriteriaId":"357AA433-37E8-4323-BFB2-3038D6E4B414"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/33a7d698f30fa0b99d50569e9909d3baa65d8f6a","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/7b3a34f08d11e7f05cd00b8e09adaa15192f0ad1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/99d348b82bcb36171f24411d3f1a15706a2a937a","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/9ef384ed300d1bcfb23d0ab0b487d544444d4b52","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/a8a917058faf4abaec9fb614bb6d5f8fe3529ec6","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/a9e164bd160be8cbee1df70acb379129e3cd2e7c","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/c1e63117711977cc4295b2ce73de29dd17066c82","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/fd7974c547abfb03072a4ee706d3a6f182266f89","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/33a7d698f30fa0b99d50569e9909d3baa65d8f6a","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/7b3a34f08d11e7f05cd00b8e09adaa15192f0ad1","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/99d348b82bcb36171f24411d3f1a15706a2a937a","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/9ef384ed300d1bcfb23d0ab0b487d544444d4b52","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/a8a917058faf4abaec9fb614bb6d5f8fe3529ec6","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/a9e164bd160be8cbee1df70acb379129e3cd2e7c","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/c1e63117711977cc4295b2ce73de29dd17066c82","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/fd7974c547abfb03072a4ee706d3a6f182266f89","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"]}]}}]}