{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31769", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.140Z", "datePublished": "2026-05-01T14:14:58.617Z", "dateUpdated": "2026-08-05T12:25:02.500Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:25:02.500Z" }, "descriptions": [ { "lang": "en", "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->big_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->descriptors_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 -> 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." } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is reached through local `/dev/gpibN` character-device ioctls such as `IBRD`, `IBWRT`, `IBCMD`, `IBWAIT`, and `IBCLOSEDEV`. There is no network, adjacent, or physical packet-processing entry point for this bug.\nAC:L - The attacker controls both sides of the race by issuing concurrent ioctls on the same GPIB file descriptor and handle. Use-after-free triggering does not depend on conditions outside attacker control once the board is online and accessible.\nPR:L - The vulnerable ioctls do not perform capability checks; a local user with access to the GPIB device node can open a descriptor, run IO or wait operations, and concurrently close it. Administrative privileges are needed for board configuration, but not for the vulnerable open/close/IO path in a configured deployment.\nUI:N - No victim action is required after the attacker has local access to the device. Exploitation is performed entirely by attacker-controlled ioctl calls.\nS:U - The bug is a kernel use-after-free reachable from a local kernel device interface and impacts the same kernel security authority. It does not cross a virtualization, IOMMU, or separate security-scope boundary.\nC:H - This is a kernel heap use-after-free of `struct gpib_descriptor`, and freed object reuse can expose or help derive kernel memory contents. Following the required kernel guidance, use-after-free bugs are scored as high confidentiality impact.\nI:H - The stale descriptor pointer is dereferenced after free and can be overlapped through heap reuse, giving a plausible path to corrupt kernel data or build write/control-flow primitives. Following the required kernel guidance, use-after-free bugs are scored as high integrity impact.\nA:H - The stale pointer can be dereferenced after `kfree()` during IO or wait completion, making kernel oops, panic, or hang plausible. Use-after-free bugs are therefore high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/gpib/common/gpib_os.c", "drivers/gpib/include/gpib_types.h" ], "versions": [ { "version": "9dde4559e93955ccc47d588f7fd051684d55c4e7", "lessThan": "cae26eff1b56d78bed7873cf3e60a2b1bdd4da6c", "status": "affected", "versionType": "git" }, { "version": "9dde4559e93955ccc47d588f7fd051684d55c4e7", "lessThan": "28c75dd143ead62e0dfac564c79d251e21d5d74b", "status": "affected", "versionType": "git" }, { "version": "9dde4559e93955ccc47d588f7fd051684d55c4e7", "lessThan": "d1857f8296dceb75d00ab857fc3c61bc00c7f5c6", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/gpib/common/gpib_os.c", "drivers/gpib/include/gpib_types.h" ], "versions": [ { "version": "6.13", "status": "affected" }, { "version": "0", "lessThan": "6.13", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.22", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.12", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.19.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/cae26eff1b56d78bed7873cf3e60a2b1bdd4da6c" }, { "url": "https://git.kernel.org/stable/c/28c75dd143ead62e0dfac564c79d251e21d5d74b" }, { "url": "https://git.kernel.org/stable/c/d1857f8296dceb75d00ab857fc3c61bc00c7f5c6" } ], "title": "gpib: fix use-after-free in IO ioctl handlers", "x_generator": { "engine": "bippy-1.2.0" } } } }