Vulnerability-Lookup

FKIE_CVE-2026-31769

Vulnerability from fkie_nvd - Published: 2026-05-01 15:16 - Updated: 2026-05-11 17:56

Severity ?

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: gpib: fix use-after-free in IO ioctl handlers The IBRD, IBWRT, IBCMD, and IBWAIT ioctl handlers use a gpib_descriptor pointer after board->big_gpib_mutex has been released. A concurrent IBCLOSEDEV ioctl can free the descriptor via close_dev_ioctl() during this window, causing a use-after-free. The IO handlers (read_ioctl, write_ioctl, command_ioctl) explicitly release big_gpib_mutex before calling their handler. wait_ioctl() is called with big_gpib_mutex held, but ibwait() releases it internally when wait_mask is non-zero. In all four cases, the descriptor pointer obtained from handle_to_descriptor() becomes unprotected. Fix this by introducing a kernel-only descriptor_busy reference count in struct gpib_descriptor. Each handler atomically increments descriptor_busy under file_priv->descriptors_mutex before releasing the lock, and decrements it when done. close_dev_ioctl() checks descriptor_busy under the same lock and rejects the close with -EBUSY if the count is non-zero. A reference count rather than a simple flag is necessary because multiple handlers can operate on the same descriptor concurrently (e.g. IBRD and IBWAIT on the same handle from different threads). A separate counter is needed because io_in_progress can be cleared from unprivileged userspace via the IBWAIT ioctl (through general_ibstatus() with set_mask containing CMPL), which would allow an attacker to bypass a check based solely on io_in_progress. The new descriptor_busy counter is only modified by the kernel IO paths. The lock ordering is consistent (big_gpib_mutex -> descriptors_mutex) and the handlers only hold descriptors_mutex briefly during the lookup, so there is no deadlock risk and no impact on IO throughput.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/28c75dd143ead62e0dfac564c79d251e21d5d74b	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/cae26eff1b56d78bed7873cf3e60a2b1bdd4da6c	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/d1857f8296dceb75d00ab857fc3c61bc00c7f5c6	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0

JSON

To clipboard

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngpib: fix use-after-free in IO ioctl handlers\n\nThe IBRD, IBWRT, IBCMD, and IBWAIT ioctl handlers use a gpib_descriptor\npointer after board-\u003ebig_gpib_mutex has been released.  A concurrent\nIBCLOSEDEV ioctl can free the descriptor via close_dev_ioctl() during\nthis window, causing a use-after-free.\n\nThe IO handlers (read_ioctl, write_ioctl, command_ioctl) explicitly\nrelease big_gpib_mutex before calling their handler.  wait_ioctl() is\ncalled with big_gpib_mutex held, but ibwait() releases it internally\nwhen wait_mask is non-zero.  In all four cases, the descriptor pointer\nobtained from handle_to_descriptor() becomes unprotected.\n\nFix this by introducing a kernel-only descriptor_busy reference count\nin struct gpib_descriptor.  Each handler atomically increments\ndescriptor_busy under file_priv-\u003edescriptors_mutex before releasing the\nlock, and decrements it when done.  close_dev_ioctl() checks\ndescriptor_busy under the same lock and rejects the close with -EBUSY\nif the count is non-zero.\n\nA reference count rather than a simple flag is necessary because\nmultiple handlers can operate on the same descriptor concurrently\n(e.g. IBRD and IBWAIT on the same handle from different threads).\n\nA separate counter is needed because io_in_progress can be cleared from\nunprivileged userspace via the IBWAIT ioctl (through general_ibstatus()\nwith set_mask containing CMPL), which would allow an attacker to bypass\na check based solely on io_in_progress.  The new descriptor_busy\ncounter is only modified by the kernel IO paths.\n\nThe lock ordering is consistent (big_gpib_mutex -\u003e descriptors_mutex)\nand the handlers only hold descriptors_mutex briefly during the lookup,\nso there is no deadlock risk and no impact on IO throughput."
    }
  ],
  "id": "CVE-2026-31769",
  "lastModified": "2026-05-11T17:56:52.220",
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          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
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  "published": "2026-05-01T15:16:40.090",
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          "lang": "en",
          "value": "CWE-416"
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      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2026-31769 (GCVE-0-2026-31769)

Vulnerability from cvelistv5 – Published: 2026-05-01 14:14 – Updated: 2026-05-11 22:15

Title

gpib: fix use-after-free in IO ioctl handlers

Summary

Severity ?

7.8 (High)


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

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/cae26eff1b56d78be…
https://git.kernel.org/stable/c/28c75dd143ead62e0…
https://git.kernel.org/stable/c/d1857f8296dceb75d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9dde4559e93955ccc47d588f7fd051684d55c4e7 , < cae26eff1b56d78bed7873cf3e60a2b1bdd4da6c (git) Affected: 9dde4559e93955ccc47d588f7fd051684d55c4e7 , < 28c75dd143ead62e0dfac564c79d251e21d5d74b (git) Affected: 9dde4559e93955ccc47d588f7fd051684d55c4e7 , < d1857f8296dceb75d00ab857fc3c61bc00c7f5c6 (git)
Linux	Linux	Affected: 6.13 Unaffected: 0 , < 6.13 (semver) Unaffected: 6.18.22 , ≤ 6.18.* (semver) Unaffected: 6.19.12 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

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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.

Action not permitted

FKIE_CVE-2026-31769

CVE-2026-31769 (GCVE-0-2026-31769)

Tags

Sightings

Nomenclature