Vulnerability-Lookup

GHSA-HM85-HR96-4GWF

Vulnerability from github – Published: 2024-08-21 09:31 – Updated: 2024-08-29 03:30

Details

In the Linux kernel, the following vulnerability has been resolved:

sched/core: Fix use-after-free bug in dup_user_cpus_ptr()

Since commit 07ec77a1d4e8 ("sched: Allow task CPU affinity to be restricted on asymmetric systems"), the setting and clearing of user_cpus_ptr are done under pi_lock for arm64 architecture. However, dup_user_cpus_ptr() accesses user_cpus_ptr without any lock protection. Since sched_setaffinity() can be invoked from another process, the process being modified may be undergoing fork() at the same time. When racing with the clearing of user_cpus_ptr in __set_cpus_allowed_ptr_locked(), it can lead to user-after-free and possibly double-free in arm64 kernel.

Commit 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask") fixes this problem as user_cpus_ptr, once set, will never be cleared in a task's lifetime. However, this bug was re-introduced in commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in do_set_cpus_allowed(). This time, it will affect all arches.

Fix this bug by always clearing the user_cpus_ptr of the newly cloned/forked task before the copying process starts and check the user_cpus_ptr state of the source task under pi_lock.

Note to stable, this patch won't be applicable to stable releases. Just copy the new dup_user_cpus_ptr() function over.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2022-48892"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-415"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-08-21T07:15:05Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/core: Fix use-after-free bug in dup_user_cpus_ptr()\n\nSince commit 07ec77a1d4e8 (\"sched: Allow task CPU affinity to be\nrestricted on asymmetric systems\"), the setting and clearing of\nuser_cpus_ptr are done under pi_lock for arm64 architecture. However,\ndup_user_cpus_ptr() accesses user_cpus_ptr without any lock\nprotection. Since sched_setaffinity() can be invoked from another\nprocess, the process being modified may be undergoing fork() at\nthe same time.  When racing with the clearing of user_cpus_ptr in\n__set_cpus_allowed_ptr_locked(), it can lead to user-after-free and\npossibly double-free in arm64 kernel.\n\nCommit 8f9ea86fdf99 (\"sched: Always preserve the user requested\ncpumask\") fixes this problem as user_cpus_ptr, once set, will never\nbe cleared in a task\u0027s lifetime. However, this bug was re-introduced\nin commit 851a723e45d1 (\"sched: Always clear user_cpus_ptr in\ndo_set_cpus_allowed()\") which allows the clearing of user_cpus_ptr in\ndo_set_cpus_allowed(). This time, it will affect all arches.\n\nFix this bug by always clearing the user_cpus_ptr of the newly\ncloned/forked task before the copying process starts and check the\nuser_cpus_ptr state of the source task under pi_lock.\n\nNote to stable, this patch won\u0027t be applicable to stable releases.\nJust copy the new dup_user_cpus_ptr() function over.",
  "id": "GHSA-hm85-hr96-4gwf",
  "modified": "2024-08-29T03:30:49Z",
  "published": "2024-08-21T09:31:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-48892"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7b5cc7fd1789ea5dbb942c9f8207b076d365badc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/87ca4f9efbd7cc649ff43b87970888f2812945b8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b22faa21b6230d5eccd233e1b7e0026a5002b287"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2022-48892 (GCVE-0-2022-48892)

Vulnerability from cvelistv5 – Published: 2024-08-21 06:10 – Updated: 2026-08-05 08:52

Title

sched/core: Fix use-after-free bug in dup_user_cpus_ptr()

Summary

In the Linux kernel, the following vulnerability has been resolved: sched/core: Fix use-after-free bug in dup_user_cpus_ptr() Since commit 07ec77a1d4e8 ("sched: Allow task CPU affinity to be restricted on asymmetric systems"), the setting and clearing of user_cpus_ptr are done under pi_lock for arm64 architecture. However, dup_user_cpus_ptr() accesses user_cpus_ptr without any lock protection. Since sched_setaffinity() can be invoked from another process, the process being modified may be undergoing fork() at the same time. When racing with the clearing of user_cpus_ptr in __set_cpus_allowed_ptr_locked(), it can lead to user-after-free and possibly double-free in arm64 kernel. Commit 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask") fixes this problem as user_cpus_ptr, once set, will never be cleared in a task's lifetime. However, this bug was re-introduced in commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in do_set_cpus_allowed(). This time, it will affect all arches. Fix this bug by always clearing the user_cpus_ptr of the newly cloned/forked task before the copying process starts and check the user_cpus_ptr state of the source task under pi_lock. Note to stable, this patch won't be applicable to stable releases. Just copy the new dup_user_cpus_ptr() function over.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-09-10 16:04 UTC

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/b22faa21b6230d5ec…
https://git.kernel.org/stable/c/7b5cc7fd1789ea5db…
https://git.kernel.org/stable/c/87ca4f9efbd7cc649…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 07ec77a1d4e82526e1588979fff2f024f8e96df2 , < b22faa21b6230d5eccd233e1b7e0026a5002b287 (git) Affected: 07ec77a1d4e82526e1588979fff2f024f8e96df2 , < 7b5cc7fd1789ea5dbb942c9f8207b076d365badc (git) Affected: 07ec77a1d4e82526e1588979fff2f024f8e96df2 , < 87ca4f9efbd7cc649ff43b87970888f2812945b8 (git)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 5.15.89 , ≤ 5.15.* (semver) Unaffected: 6.1.7 , ≤ 6.1.* (semver) Unaffected: 6.2 , ≤ * (original_commit_for_fix)

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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