CVE-2026-31756

Description

In the Linux kernel, the following vulnerability has been resolved: usb: dwc2: gadget: Fix spin_lock/unlock mismatch in dwc2_hsotg_udc_stop() dwc2_gadget_exit_clock_gating() internally calls call_gadget() macro, which expects hsotg->lock to be held since it does spin_unlock/spin_lock around the gadget driver callback invocation. However, dwc2_hsotg_udc_stop() calls dwc2_gadget_exit_clock_gating() without holding the lock. This leads to: - spin_unlock on a lock that is not held (undefined behavior) - The lock remaining held after dwc2_gadget_exit_clock_gating() returns, causing a deadlock when spin_lock_irqsave() is called later in the same function. Fix this by acquiring hsotg->lock before calling dwc2_gadget_exit_clock_gating() and releasing it afterwards, which satisfies the locking requirement of the call_gadget() macro.

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 (修复前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC Simulation for CVE-2026-31756
 * This code demonstrates the logic error causing the deadlock.
 * It is a simplified representation of the vulnerable kernel code.
 */

#include <linux/spinlock.h>

struct hsotg {
    spinlock_t lock;
};

/* Simulates the call_gadget() macro behavior */
void call_gadget_mock(struct hsotg *hsotg) {
    // Expects lock to be held
    spin_unlock(&hsotg->lock);
    // ... gadget callback ...
    spin_lock(&hsotg->lock);
}

/* Simulates dwc2_gadget_exit_clock_gating */
void vulnerable_function(struct hsotg *hsotg) {
    call_gadget_mock(hsotg);
}

/* Simulates dwc2_hsotg_udc_stop (The Vulnerable Caller) */
void trigger_vulnerability(struct hsotg *hsotg) {
    unsigned long flags;

    // VULNERABILITY: Calls vulnerable_function WITHOUT holding hsotg->lock first.
    // This leads to spin_unlock on an unlocked lock (undefined behavior)
    // and leaves the lock held afterwards.
    vulnerable_function(hsotg);

    // Later in the function, tries to acquire the lock
    spin_lock_irqsave(&hsotg->lock, flags);
    // DEADLOCK occurs here because the lock is already held.
    spin_unlock_irqrestore(&hsotg->lock, flags);
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31756
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31756
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31756/
[4] VulDB https://vuldb.com/cve/CVE-2026-31756
[5] https://git.kernel.org/stable/c/4ed9d2dd9f29828c311db6ec4b8e0d34bfd6d6a4
[6] https://git.kernel.org/stable/c/51b62286fc668c6eb74dee7624ec0beec3c5a0ed
[7] https://git.kernel.org/stable/c/61937f686290494998236c680ce0836b8dd63a3f
[8] https://git.kernel.org/stable/c/8ffe31acb3b77a30ae34d01719a269881569fb7f
[9] https://git.kernel.org/stable/c/9bb4b5ed7f8c4f95cc556bdf042b0ba2fa13557a
[10] https://git.kernel.org/stable/c/beab10429439e20708036a66fb0d97ffb79da6a1
[11] https://git.kernel.org/stable/c/e9fcca3e87463013d595c65c2189ffaa32ad3b50

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31756", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:38.580", "lastModified": "2026-05-08T18:30:40.390", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: dwc2: gadget: Fix spin_lock/unlock mismatch in dwc2_hsotg_udc_stop()\n\ndwc2_gadget_exit_clock_gating() internally calls call_gadget() macro,\nwhich expects hsotg->lock to be held since it does spin_unlock/spin_lock\naround the gadget driver callback invocation.\n\nHowever, dwc2_hsotg_udc_stop() calls dwc2_gadget_exit_clock_gating()\nwithout holding the lock. This leads to:\n - spin_unlock on a lock that is not held (undefined behavior)\n - The lock remaining held after dwc2_gadget_exit_clock_gating() returns,\n causing a deadlock when spin_lock_irqsave() is called later in the\n same function.\n\nFix this by acquiring hsotg->lock before calling\ndwc2_gadget_exit_clock_gating() and releasing it afterwards, which\nsatisfies the locking requirement of the call_gadget() macro."}], "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": "CWE-667"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.187", "versionEndExcluding": "5.15.203", "matchCriteriaId": "47F2AD8D-1BF2-49F3-AB68-24C4630BAFD0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.143", "versionEndExcluding": "6.1.168", "matchCriteriaId": "7E908ADC-45DA-494F-9E71-A310F56EDCAF"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.96", "versionEndExcluding": "6.6.134", "matchCriteriaId": "E220ECC5-ECBC-4EFF-B943-1DEACE981592"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.36", "versionEndExcluding": "6.12.81", "matchCriteriaId": "0FFEF924-DF26-4B6A-B663-70084F25414E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15.5", "versionEndExcluding": "6.18.22", "matchCriteriaId": "8F8BB240-724D-4162-8196-2D2F2C5C8724"}, {"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/4ed9d2dd9f29828c311db6ec4b8e0d34bfd6d6a4", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/51b62286fc668c6eb74dee7624ec0beec3c5a0ed", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/61937f686290494998236c680ce0836b8dd63a3f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/8ffe31acb3b77a30ae34d01719a269881569fb7f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9bb4b5ed7f8c4f95cc556bdf042b0ba2fa13557a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/beab10429439e20708036a66fb0d97ffb79da6a1", "source": "416baaa9-dc9f-4396-8d5f-8c0 ... 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