CVE-2026-31467

Description

In the Linux kernel, the following vulnerability has been resolved: erofs: add GFP_NOIO in the bio completion if needed The bio completion path in the process context (e.g. dm-verity) will directly call into decompression rather than trigger another workqueue context for minimal scheduling latencies, which can then call vm_map_ram() with GFP_KERNEL. Due to insufficient memory, vm_map_ram() may generate memory swapping I/O, which can cause submit_bio_wait to deadlock in some scenarios. Trimmed down the call stack, as follows: f2fs_submit_read_io submit_bio //bio_list is initialized. mmc_blk_mq_recovery z_erofs_endio vm_map_ram __pte_alloc_kernel __alloc_pages_direct_reclaim shrink_folio_list __swap_writepage submit_bio_wait //bio_list is non-NULL, hang!!! Use memalloc_noio_{save,restore}() to wrap up this path.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (修复提交前)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * Conceptual PoC for CVE-2026-31467 (Linux Kernel EROFS Deadlock)
 * This is a simulation of the trigger condition.
 * Actual exploitation requires specific kernel memory pressure and EROFS mount.
 */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

// Note: This PoC demonstrates the user-space trigger logic (memory pressure).
// The actual deadlock happens in the kernel space within z_erofs_endio.

void consume_memory() {
    size_t block_size = 1024 * 1024; // 1MB
    char *buf;
    int i = 0;
    printf("[+] Applying memory pressure to trigger OOM/Swap...\n");
    while (1) {
        buf = malloc(block_size);
        if (buf == NULL) break;
        memset(buf, 0xAA, block_size);
        i++;
        if (i % 100 == 0) printf("Allocated %d MB\n", i);
    }
    printf("[-] Memory allocation stopped. Kernel may start swapping during EROFS access.\n");
}

int main() {
    printf("CVE-2026-31467 PoC Trigger Simulation\n");
    printf("Scenario: Mount EROFS image with dm-verity on low memory system.\n");
    
    // Step 1: Consume memory to force GFP_KERNEL to trigger swap
    consume_memory();

    // Step 2: Perform I/O on EROFS mount (Kernel space execution)
    // In a real exploit, this would be a read() on a file on the EROFS filesystem
    // causing the bio completion path to call vm_map_ram() with GFP_KERNEL.
    printf("[!] Triggering EROFS I/O (Simulation)...\n");
    
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31467
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31467
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31467/
[4] VulDB https://vuldb.com/cve/CVE-2026-31467
[5] https://git.kernel.org/stable/c/378949f46e897204384f3f5f91e42e93e3f87568
[6] https://git.kernel.org/stable/c/5c8ecdcfbfb0b0c6a82a4ebadc1ddea61609b902
[7] https://git.kernel.org/stable/c/c23df30915f83e7257c8625b690a1cece94142a0
[8] https://git.kernel.org/stable/c/d6565ea662e17d45a577184b0011bd69de22dc2b
[9] https://git.kernel.org/stable/c/d9d8360cb66e3b599d89d2526e7da8b530ebf2ff
[10] https://git.kernel.org/stable/c/da40464064599eefe78749f75cd2bba371044c04
[11] https://git.kernel.org/stable/c/e83e20b82859f0588e9a52a6fa9fea704a2061cf

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31467", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:42.977", "lastModified": "2026-05-07T18:21:40.090", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: add GFP_NOIO in the bio completion if needed\n\nThe bio completion path in the process context (e.g. dm-verity)\nwill directly call into decompression rather than trigger another\nworkqueue context for minimal scheduling latencies, which can\nthen call vm_map_ram() with GFP_KERNEL.\n\nDue to insufficient memory, vm_map_ram() may generate memory\nswapping I/O, which can cause submit_bio_wait to deadlock\nin some scenarios.\n\nTrimmed down the call stack, as follows:\n\nf2fs_submit_read_io\n submit_bio //bio_list is initialized.\n mmc_blk_mq_recovery\n z_erofs_endio\n vm_map_ram\n __pte_alloc_kernel\n __alloc_pages_direct_reclaim\n shrink_folio_list\n __swap_writepage\n submit_bio_wait //bio_list is non-NULL, hang!!!\n\nUse memalloc_noio_{save,restore}() to wrap up this path."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "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": "5.13", "versionEndExcluding": "5.15.203", "matchCriteriaId": "985804EB-66D2-4D4A-AF5D-D7A87E940EEE"}, {"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: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/378949f46e897204384f3f5f91e42e93e3f87568", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5c8ecdcfbfb0b0c6a82a4ebadc1ddea61609b902", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/c23df30915f83e7257c8625b690a1cece94142a0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d6565ea662e17d45a577184b0011bd69de22dc2b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d9d8360cb66e3b599d89d2526e7da8b530ebf2ff", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/da40464064599eefe78749f75cd2bba371044c04", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e83e20b82859f0588e9a52a6fa9fea704a2061cf", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Pa ... (truncated)