CVE-2026-31464

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done() A malicious or compromised VIO server can return a num_written value in the discover targets MAD response that exceeds max_targets. This value is stored directly in vhost->num_targets without validation, and is then used as the loop bound in ibmvfc_alloc_targets() to index into disc_buf[], which is only allocated for max_targets entries. Indices at or beyond max_targets access kernel memory outside the DMA-coherent allocation. The out-of-bounds data is subsequently embedded in Implicit Logout and PLOGI MADs that are sent back to the VIO server, leaking kernel memory. Fix by clamping num_written to max_targets before storing it.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (特定版本，参考Git提交修复记录)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * Conceptual PoC for Vulnerable Logic in ibmvfc
 * This snippet demonstrates the lack of bounds check.
 */

void ibmvfc_discover_targets_done(struct ibmvfc_event *event) {
    struct ibmvfc_host *vhost = event->vhost;
    struct ibmvfc_discover_targets *srp = &vhost->disc_buf;
    
    // Vulnerability: num_written from VIO server is not validated against max_targets
    u32 num_written = be32_to_cpu(srp->mad.common.status);
    
    // Direct assignment without clamping
    vhost->num_targets = num_written; 
    
    // This leads to OOB access in ibmvfc_alloc_targets if num_written > max_targets
    if (num_written > vhost->max_targets) {
        // Missing check in vulnerable version
        printk(KERN_ERR "Potential OOB access detected: %d > %d\n", num_written, vhost->max_targets);
    }
}

/*
 * Fix Implementation (Clamping)
 */
void ibmvfc_discover_targets_done_fixed(struct ibmvfc_event *event) {
    struct ibmvfc_host *vhost = event->vhost;
    struct ibmvfc_discover_targets *srp = &vhost->disc_buf;
    u32 num_written = be32_to_cpu(srp->mad.common.status);
    
    // Fix: Clamp num_written to max_targets
    if (num_written > vhost->max_targets) {
        dev_warn(vhost->dev, "Discover targets response exceeded max_targets, clamping\n");
        num_written = vhost->max_targets;
    }
    
    vhost->num_targets = num_written;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31464
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31464
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31464/
[4] VulDB https://vuldb.com/cve/CVE-2026-31464
[5] https://git.kernel.org/stable/c/394a1cac3c12fdd7d77f19ccfd222ab5ff87ef89
[6] https://git.kernel.org/stable/c/4ed727e35b0ab17d3eeeb1e8023768396e2be161
[7] https://git.kernel.org/stable/c/61d099ac4a7a8fb11ebdb6e2ec8d77f38e77362f
[8] https://git.kernel.org/stable/c/786f10b1966e485046839f992e89f2c18cbd1983
[9] https://git.kernel.org/stable/c/a007246cb6c9ebdc93dafbf63cc2d43d98f402cc
[10] https://git.kernel.org/stable/c/bae4df0a643fa7f84663473aa3082a9c2ed139db
[11] https://git.kernel.org/stable/c/d1466bf991b2343cf2ba8336e440c8faf3cbb780
[12] https://git.kernel.org/stable/c/d842348f8a00d5b1d7358f207eb34ffcf5b16df3

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31464", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:42.450", "lastModified": "2026-05-07T18:28:45.780", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()\n\nA malicious or compromised VIO server can return a num_written value in the\ndiscover targets MAD response that exceeds max_targets. This value is\nstored directly in vhost->num_targets without validation, and is then used\nas the loop bound in ibmvfc_alloc_targets() to index into disc_buf[], which\nis only allocated for max_targets entries. Indices at or beyond max_targets\naccess kernel memory outside the DMA-coherent allocation. The\nout-of-bounds data is subsequently embedded in Implicit Logout and PLOGI\nMADs that are sent back to the VIO server, leaking kernel memory.\n\nFix by clamping num_written to max_targets before storing it."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "5.10.253", "matchCriteriaId": "A01FA99D-A279-4156-BCB7-C23B63339A60"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"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/394a1cac3c12fdd7d77f19ccfd222ab5ff87ef89", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4ed727e35b0ab17d3eeeb1e8023768396e2be161", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/61d099ac4a7a8fb11ebdb6e2ec8d77f38e77362f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/786f10b1966e485046839f992e89f2c18cbd1983", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/a007246cb6c9ebdc93dafbf63cc2d43d98f402cc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bae4df0a643fa7f84663473aa3082a9c2ed139db", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d1466bf991b2343cf2ba8336e440c8faf3cbb780", "source": "416baaa9-dc9f ... 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