Vulnerability-Lookup

GHSA-4366-C9HW-R9QG

Vulnerability from github – Published: 2024-09-18 09:30 – Updated: 2024-09-23 18:30

Details

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

xen: privcmd: Fix possible access to a freed kirqfd instance

Nothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and privcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd created and added to the irqfds_list by privcmd_irqfd_assign() may get removed by another thread executing privcmd_irqfd_deassign(), while the former is still using it after dropping the locks.

This can lead to a situation where an already freed kirqfd instance may be accessed and cause kernel oops.

Use SRCU locking to prevent the same, as is done for the KVM implementation for irqfds.

Severity

5.5 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2024-46762"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-09-18T08:15:04Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nxen: privcmd: Fix possible access to a freed kirqfd instance\n\nNothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and\nprivcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd\ncreated and added to the irqfds_list by privcmd_irqfd_assign() may get\nremoved by another thread executing privcmd_irqfd_deassign(), while the\nformer is still using it after dropping the locks.\n\nThis can lead to a situation where an already freed kirqfd instance may\nbe accessed and cause kernel oops.\n\nUse SRCU locking to prevent the same, as is done for the KVM\nimplementation for irqfds.",
  "id": "GHSA-4366-c9hw-r9qg",
  "modified": "2024-09-23T18:30:34Z",
  "published": "2024-09-18T09:30:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-46762"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/112fd2f02b308564724b8e81006c254d20945c4b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/611ff1b1ae989a7bcce3e2a8e132ee30e968c557"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e997b357b13a7d95de31681fc54fcc34235fa527"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2024-46762 (GCVE-0-2024-46762)

Vulnerability from cvelistv5 – Published: 2024-09-18 07:12 – Updated: 2026-08-05 11:38

Title

xen: privcmd: Fix possible access to a freed kirqfd instance

Summary

In the Linux kernel, the following vulnerability has been resolved: xen: privcmd: Fix possible access to a freed kirqfd instance Nothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and privcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd created and added to the irqfds_list by privcmd_irqfd_assign() may get removed by another thread executing privcmd_irqfd_deassign(), while the former is still using it after dropping the locks. This can lead to a situation where an already freed kirqfd instance may be accessed and cause kernel oops. Use SRCU locking to prevent the same, as is done for the KVM implementation for irqfds.

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 2024-09-29 14:43 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7018 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/e997b357b13a7d95d…
https://git.kernel.org/stable/c/112fd2f02b3085647…
https://git.kernel.org/stable/c/611ff1b1ae989a7bc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6 , < e997b357b13a7d95de31681fc54fcc34235fa527 (git) Affected: f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6 , < 112fd2f02b308564724b8e81006c254d20945c4b (git) Affected: f8941e6c4c712948663ec5d7bbb546f1a0f4e3f6 , < 611ff1b1ae989a7bcce3e2a8e132ee30e968c557 (git)
Linux	Linux	Affected: 6.6 Unaffected: 0 , < 6.6 (semver) Unaffected: 6.6.51 , ≤ 6.6.* (semver) Unaffected: 6.10.10 , ≤ 6.10.* (semver) Unaffected: 6.11 , ≤ * (original_commit_for_fix)

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                "id": "CVE-2024-46762",
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                "timestamp": "2024-09-29T14:43:33.478974Z",
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              "version": "6.11",
              "versionType": "original_commit_for_fix"
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        }
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              "value": "AV:L - The vulnerability is reached only through `ioctl(IOCTL_PRIVCMD_IRQFD)` on the `/dev/xen/privcmd` character device, requiring local access to the system. No remote or adjacent-network path exists to `privcmd_ioctl_irqfd()`.\nAC:L - The attacker controls both sides of the race, issuing the assign and deassign ioctls concurrently from its own threads on the same eventfd, and can retry in a tight loop; the window is further widened by the workqueue handoff to `irqfd_shutdown()` and the preemptible `HYPERVISOR_dm_op()` call in `irqfd_inject()`.\nPR:L - `privcmd_ioctl()` performs no capability check whatsoever \u2014 only the device-node permission gates access \u2014 and the `IOCTL_PRIVCMD_RESTRICT` design explicitly hands a privcmd fd to deprivileged device-model/virtio-backend daemons, which is exactly the scenario the irqfd interface was built for, so an unprivileged local process holding that fd can trigger the UAF.\nUI:N - The attacker performs the entire sequence itself with two concurrent ioctls on descriptors it owns; no action by any other user or victim process is needed.\nS:U - The use-after-free corrupts kernel memory in the same domain that hosts the calling process, giving standard local kernel privilege escalation rather than crossing the Xen guest/host or IOMMU boundary.\nC:H - The freed `privcmd_kernel_irqfd` is left registered in the eventfd wait queue and is re-read (`kirqfd-\u003eeventfd`, `kirqfd-\u003exbufs`, `wait-\u003efunc`) after `kfree()`, and the attacker chooses the allocation size via the unbounded `irqfd-\u003esize`, so resprayed slab contents can be leveraged into arbitrary kernel memory disclosure.\nI:H - `add_wait_queue_priority()` writes list pointers into the freed chunk and `kirqfd-\u003eerror = rc` writes into it as well, while the dangling wait-queue entry causes a later `eventfd_signal()` to call a function pointer read from attacker-resprayed memory \u2014 a control-flow hijack / arbitrary-write primitive.\nA:H - The commit itself states the freed `kirqfd` access \"can lead to a situation where an already freed kirqfd instance may be accessed and cause kernel oops\"; the corrupted wait-queue list and freed `eventfd_ctx` reliably panic the kernel even without full exploitation."
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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.

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