CVE-2021-47461

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a race between writeprotect and exit_mmap() A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called. The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well. Use mmget_not_zero() to prevent the race as done in other userfaultfd operations.

CVSS v3 4.7 MEDIUM

4.7^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.0 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a	Patch
https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525	Patch
https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca	Patch
https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a	Patch
https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525	Patch
https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:5.15:rc1::::::
	cpe:2.3:o:linux:linux_kernel:5.15:rc2::::::
	cpe:2.3:o:linux:linux_kernel:5.15:rc3::::::
	cpe:2.3:o:linux:linux_kernel:5.15:rc4::::::
	cpe:2.3:o:linux:linux_kernel:5.15:rc5::::::
	cpe:2.3:o:linux:linux_kernel:5.15:rc6::::::

History

No history.

Information

Published : 2024-05-22 07:15

Updated : 2025-09-24 12:38

NVD link : CVE-2021-47461

Mitre link : CVE-2021-47461

CVE.ORG link : CVE-2021-47461

JSON object : View

Products Affected

linux

linux_kernel

CWE

CWE-362

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

{"id": "CVE-2021-47461", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "[email protected]", "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": "2024-05-22T07:15:11.040", "references": [{"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "[email protected]", "description": [{"lang": "en", "value": "CWE-362"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: fix a race between writeprotect and exit_mmap()\n\nA race is possible when a process exits, its VMAs are removed by\nexit_mmap() and at the same time userfaultfd_writeprotect() is called.\n\nThe race was detected by KASAN on a development kernel, but it appears\nto be possible on vanilla kernels as well.\n\nUse mmget_not_zero() to prevent the race as done in other userfaultfd\noperations."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: userfaultfd: corrige una ejecuci\u00f3n entre writeprotect y exit_mmap() Una ejecuci\u00f3n es posible cuando un proceso sale, sus VMA son eliminados por exit_mmap() y al mismo tiempo se llama a userfaultfd_writeprotect() . KASAN detect\u00f3 la ejecuci\u00f3n en un n\u00facleo de desarrollo, pero parece ser posible tambi\u00e9n en n\u00facleos de vainilla. Utilice mmget_not_zero() para evitar la ejecuci\u00f3n como se hace en otras operaciones de userfaultfd."}], "lastModified": "2025-09-24T12:38:42.240", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "337EB464-BC23-4BF5-B901-A933B3ABA6A7", "versionEndExcluding": "5.10.76", "versionStartIncluding": "5.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "63BD46C4-473F-45F9-93E9-F67D955321D8", "versionEndExcluding": "5.14.15", "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"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}