CVE-2026-43115

Description

In the Linux kernel, the following vulnerability has been resolved: srcu: Use irq_work to start GP in tiny SRCU Tiny SRCU's srcu_gp_start_if_needed() directly calls schedule_work(), which acquires the workqueue pool->lock. This causes a lockdep splat when call_srcu() is called with a scheduler lock held, due to: call_srcu() [holding pi_lock] srcu_gp_start_if_needed() schedule_work() -> pool->lock workqueue_init() / create_worker() [holding pool->lock] wake_up_process() -> try_to_wake_up() -> pi_lock Also add irq_work_sync() to cleanup_srcu_struct() to prevent a use-after-free if a queued irq_work fires after cleanup begins. Tested with rcutorture SRCU-T and no lockdep warnings. [ Thanks to Boqun for similar fix in patch "rcu: Use an intermediate irq_work to start process_srcu()" ]

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

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* - VULNERABLE

Linux Kernel (Fixed by commit a6fc88b22bc8d12ad52e8412c667ec0f5bf055af)

Linux Kernel (Fixed by commit bb37286db65368cb72ba8757ad86299c4e4a73fc)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-43115 (Conceptual)
 * This kernel module attempts to trigger the race condition in Tiny SRCU.
 * Compile with: make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/srcu.h>

static struct srcu_struct srcu;

static int __init poc_init(void)
{
    printk(KERN_INFO "CVE-2026-43115 PoC: Loading module...\n");
    init_srcu_struct(&srcu);

    // Attempt to trigger call_srcu() in a context that might stress the lock
    // Note: Triggering the specific deadlock requires precise timing/context.
    call_srcu(&srcu, NULL, NULL);

    return 0;
}

static void __exit poc_exit(void)
{
    cleanup_srcu_struct(&srcu);
    printk(KERN_INFO "CVE-2026-43115 PoC: Unloading module...\n");
}

module_init(poc_init);
module_exit(poc_exit);
MODULE_LICENSE("GPL");

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43115
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43115
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43115/
[4] VulDB https://vuldb.com/cve/CVE-2026-43115
[5] https://git.kernel.org/stable/c/a6fc88b22bc8d12ad52e8412c667ec0f5bf055af
[6] https://git.kernel.org/stable/c/bb37286db65368cb72ba8757ad86299c4e4a73fc

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43115", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T10:16:25.290", "lastModified": "2026-05-08T17:51:44.920", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsrcu: Use irq_work to start GP in tiny SRCU\n\nTiny SRCU's srcu_gp_start_if_needed() directly calls schedule_work(),\nwhich acquires the workqueue pool->lock.\n\nThis causes a lockdep splat when call_srcu() is called with a scheduler\nlock held, due to:\n\n call_srcu() [holding pi_lock]\n srcu_gp_start_if_needed()\n schedule_work() -> pool->lock\n\n workqueue_init() / create_worker() [holding pool->lock]\n wake_up_process() -> try_to_wake_up() -> pi_lock\n\nAlso add irq_work_sync() to cleanup_srcu_struct() to prevent a\nuse-after-free if a queued irq_work fires after cleanup begins.\n\nTested with rcutorture SRCU-T and no lockdep warnings.\n\n[ Thanks to Boqun for similar fix in patch \"rcu: Use an intermediate irq_work\nto start process_srcu()\" ]"}], "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": "4.12", "versionEndExcluding": "6.19.14", "matchCriteriaId": "2D2EA261-943C-485F-BC27-BE526335CA60"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/a6fc88b22bc8d12ad52e8412c667ec0f5bf055af", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bb37286db65368cb72ba8757ad86299c4e4a73fc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}