CVE-2025-71087

Description

In the Linux kernel, the following vulnerability has been resolved: iavf: fix off-by-one issues in iavf_config_rss_reg() There are off-by-one bugs when configuring RSS hash key and lookup table, causing out-of-bounds reads to memory [1] and out-of-bounds writes to device registers. Before commit 43a3d9ba34c9 ("i40evf: Allow PF driver to configure RSS"), the loop upper bounds were: i <= I40E_VFQF_{HKEY,HLUT}_MAX_INDEX which is safe since the value is the last valid index. That commit changed the bounds to: i <= adapter->rss_{key,lut}_size / 4 where `rss_{key,lut}_size / 4` is the number of dwords, so the last valid index is `(rss_{key,lut}_size / 4) - 1`. Therefore, using `<=` accesses one element past the end. Fix the issues by using `<` instead of `<=`, ensuring we do not exceed the bounds. [1] KASAN splat about rss_key_size off-by-one BUG: KASAN: slab-out-of-bounds in iavf_config_rss+0x619/0x800 Read of size 4 at addr ffff888102c50134 by task kworker/u8:6/63 CPU: 0 UID: 0 PID: 63 Comm: kworker/u8:6 Not tainted 6.18.0-rc2-enjuk-tnguy-00378-g3005f5b77652-dirty #156 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: iavf iavf_watchdog_task Call Trace: <TASK> dump_stack_lvl+0x6f/0xb0 print_report+0x170/0x4f3 kasan_report+0xe1/0x1a0 iavf_config_rss+0x619/0x800 iavf_watchdog_task+0x2be7/0x3230 process_one_work+0x7fd/0x1420 worker_thread+0x4d1/0xd40 kthread+0x344/0x660 ret_from_fork+0x249/0x320 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 63: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 __kmalloc_noprof+0x246/0x6f0 iavf_watchdog_task+0x28fc/0x3230 process_one_work+0x7fd/0x1420 worker_thread+0x4d1/0xd40 kthread+0x344/0x660 ret_from_fork+0x249/0x320 ret_from_fork_asm+0x1a/0x30 The buggy address belongs to the object at ffff888102c50100 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes to the right of allocated 52-byte region [ffff888102c50100, ffff888102c50134) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x102c50 flags: 0x200000000000000(node=0|zone=2) page_type: f5(slab) raw: 0200000000000000 ffff8881000418c0 dead000000000122 0000000000000000 raw: 0000000000000000 0000000080200020 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888102c50000: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc ffff888102c50080: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc >ffff888102c50100: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc ^ ffff888102c50180: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ffff888102c50200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

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 6.18.0-rc2 (受影响的测试版本)

iavf驱动 - commit 43a3d9ba34c9之后引入漏洞的版本

i40evf/iavf驱动在RSS配置功能引入后的版本

PoC / Exploit Code

⚠ For Security Research Only

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

python

// CVE-2025-71087 PoC - Trigger off-by-one in iavf_config_rss_reg
// This demonstrates the boundary condition that causes the vulnerability

#include <stdio.h>
#include <stdint.h>

// Simulate the vulnerable condition
void demonstrate_offbyone_vulnerability(void) {
    uint32_t rss_key_size = 52;  // Typical RSS key size
    uint32_t rss_lut_size = 128; // Typical LUT size
    
    uint32_t num_dwords_key = rss_key_size / 4;  // = 13
    uint32_t num_dwords_lut = rss_lut_size / 4;   // = 32
    
    printf("RSS Key: %d dwords, valid indices: 0 to %d\n", num_dwords_key, num_dwords_key - 1);
    printf("RSS LUT: %d dwords, valid indices: 0 to %d\n", num_dwords_lut, num_dwords_lut - 1);
    
    // Vulnerable code pattern (using <=)
    printf("\n[VULNERABLE] Loop with <= condition:\n");
    for (uint32_t i = 0; i <= num_dwords_key / 4; i++) {
        printf("  Accessing index %u (last valid: %u)\n", i, num_dwords_key - 1);
        if (i > num_dwords_key - 1) {
            printf("  *** OUT-OF-BOUNDS ACCESS at index %u! ***\n", i);
        }
    }
    
    // Fixed code pattern (using <)
    printf("\n[FIXED] Loop with < condition:\n");
    for (uint32_t i = 0; i < num_dwords_key / 4; i++) {
        printf("  Accessing index %u (safe)\n", i);
    }
}

int main() {
    printf("CVE-2025-71087 Off-by-One Vulnerability Demonstration\n");
    printf("==================================================\n\n");
    demonstrate_offbyone_vulnerability();
    return 0;
}

/*
 * To trigger the actual vulnerability:
 * 1. Use a system with iavf driver loaded
 * 2. Configure RSS with specific key/LUT sizes
 * 3. The off-by-one occurs during iavf_watchdog_task execution
 * 
 * KASAN will report:
 * BUG: KASAN: slab-out-of-bounds in iavf_config_rss+0x619/0x800
 */

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2025-71087
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2025-71087
[3] CVE Details https://www.cvedetails.com/cve/CVE-2025-71087/
[4] VulDB https://vuldb.com/cve/CVE-2025-71087
[5] https://git.kernel.org/stable/c/18de0e41d69d97fab10b91fecf10ae78a5e43232
[6] https://git.kernel.org/stable/c/3095228e1320371e143835d0cebeef1a8a754c66
[7] https://git.kernel.org/stable/c/5bb18bfd505ca1affbca921462c350095a6c798c
[8] https://git.kernel.org/stable/c/6daa2893f323981c7894c68440823326e93a7d61
[9] https://git.kernel.org/stable/c/ceb8459df28d22c225a82d74c0f725f2a935d194
[10] https://git.kernel.org/stable/c/d7369dc8dd7cbf5cee3a22610028d847b6f02982
[11] https://git.kernel.org/stable/c/f36de3045d006e6d9be1be495f2ed88d1721e752

Raw JSON Data

JSON

{"cve": {"id": "CVE-2025-71087", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-01-13T16:16:08.343", "lastModified": "2026-03-25T18:57:03.820", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niavf: fix off-by-one issues in iavf_config_rss_reg()\n\nThere are off-by-one bugs when configuring RSS hash key and lookup\ntable, causing out-of-bounds reads to memory [1] and out-of-bounds\nwrites to device registers.\n\nBefore commit 43a3d9ba34c9 (\"i40evf: Allow PF driver to configure RSS\"),\nthe loop upper bounds were:\n    i <= I40E_VFQF_{HKEY,HLUT}_MAX_INDEX\nwhich is safe since the value is the last valid index.\n\nThat commit changed the bounds to:\n    i <= adapter->rss_{key,lut}_size / 4\nwhere `rss_{key,lut}_size / 4` is the number of dwords, so the last\nvalid index is `(rss_{key,lut}_size / 4) - 1`. Therefore, using `<=`\naccesses one element past the end.\n\nFix the issues by using `<` instead of `<=`, ensuring we do not exceed\nthe bounds.\n\n[1] KASAN splat about rss_key_size off-by-one\n  BUG: KASAN: slab-out-of-bounds in iavf_config_rss+0x619/0x800\n  Read of size 4 at addr ffff888102c50134 by task kworker/u8:6/63\n\n  CPU: 0 UID: 0 PID: 63 Comm: kworker/u8:6 Not tainted 6.18.0-rc2-enjuk-tnguy-00378-g3005f5b77652-dirty #156 PREEMPT(voluntary)\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n  Workqueue: iavf iavf_watchdog_task\n  Call Trace:\n   <TASK>\n   dump_stack_lvl+0x6f/0xb0\n   print_report+0x170/0x4f3\n   kasan_report+0xe1/0x1a0\n   iavf_config_rss+0x619/0x800\n   iavf_watchdog_task+0x2be7/0x3230\n   process_one_work+0x7fd/0x1420\n   worker_thread+0x4d1/0xd40\n   kthread+0x344/0x660\n   ret_from_fork+0x249/0x320\n   ret_from_fork_asm+0x1a/0x30\n   </TASK>\n\n  Allocated by task 63:\n   kasan_save_stack+0x30/0x50\n   kasan_save_track+0x14/0x30\n   __kasan_kmalloc+0x7f/0x90\n   __kmalloc_noprof+0x246/0x6f0\n   iavf_watchdog_task+0x28fc/0x3230\n   process_one_work+0x7fd/0x1420\n   worker_thread+0x4d1/0xd40\n   kthread+0x344/0x660\n   ret_from_fork+0x249/0x320\n   ret_from_fork_asm+0x1a/0x30\n\n  The buggy address belongs to the object at ffff888102c50100\n   which belongs to the cache kmalloc-64 of size 64\n  The buggy address is located 0 bytes to the right of\n   allocated 52-byte region [ffff888102c50100, ffff888102c50134)\n\n  The buggy address belongs to the physical page:\n  page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x102c50\n  flags: 0x200000000000000(node=0|zone=2)\n  page_type: f5(slab)\n  raw: 0200000000000000 ffff8881000418c0 dead000000000122 0000000000000000\n  raw: 0000000000000000 0000000080200020 00000000f5000000 0000000000000000\n  page dumped because: kasan: bad access detected\n\n  Memory state around the buggy address:\n   ffff888102c50000: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc\n   ffff888102c50080: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc\n  >ffff888102c50100: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc\n                                       ^\n   ffff888102c50180: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc\n   ffff888102c50200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc"}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\niavf: corrige problemas de 'off-by-one' en iavf_config_rss_reg()\n\nExisten errores de 'off-by-one' al configurar la clave hash RSS y la tabla de búsqueda, causando lecturas fuera de límites a la memoria [1] y escrituras fuera de límites a los registros del dispositivo.\n\nAntes del commit 43a3d9ba34c9 ('i40evf: Permitir al controlador PF configurar RSS'), los límites superiores del bucle eran:\n    i &lt;= I40E_VFQF_{HKEY,HLUT}_MAX_INDEX\nlo cual es seguro ya que el valor es el último índice válido.\n\nEse commit cambió los límites a:\n    i &lt;= adapter-&gt;rss_{key,lut}_size / 4\ndonde 'rss_{key,lut}_size / 4' es el número de dwords, por lo que el último índice válido es '(rss_{key,lut}_size / 4) - 1'. Por lo tanto, usar '&lt;=' accede a un elemento más allá del final.\n\nSe corrigen los problemas usando '&lt;' en lugar de '&lt;=', asegurando que no excedemos los límites.\n\n[1] Informe de KASAN sobre el 'off-by-one' de rss_key_size\n  ERROR: KASAN: 'slab-out-of-bounds' en iavf_config_rss+0x619/0x800\n  Lectura de tamaño 4 en la dirección ffff888102c50134 por la tarea kworker/u8:6/63\n\n  CPU: 0 UID: 0 PID: 63 Comm: kworker/u8:6 No contaminado 6.18.0-rc2-enjuk-tnguy-00378-g3005f5b77652-dirty #156 PREEMPT(voluntario)\n  Nombre del hardware: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n  Cola de trabajo: iavf iavf_watchdog_task\n  Traza de llamadas:\n   \n   dump_stack_lvl+0x6f/0xb0\n   print_report+0x170/0x4f3\n   kasan_report+0xe1/0x1a0\n   iavf_config_rss+0x619/0x800\n   iavf_watchdog_task+0x2be7/0x3230\n   process_one_work+0x7fd/0x1420\

... (truncated)