CVE-2022-50432

Estado: ModificadaAlta (7.8)—

In the Linux kernel, the following vulnerability has been resolved:

kernfs: fix use-after-free in __kernfs_remove

Syzkaller managed to trigger concurrent calls to kernfs_remove_by_name_ns() for the same file resulting in a KASAN detected use-after-free. The race occurs when the root node is freed during kernfs_drain().

To prevent this acquire an additional reference for the root of the tree that is removed before calling __kernfs_remove().

Found by syzkaller with the following reproducer (slab_nomerge is required):

syz_mount_image$ext4(0x0, &(0x7f0000000100)='./file0\x00', 0x100000, 0x0, 0x0, 0x0, 0x0) r0 = openat(0xffffffffffffff9c, &(0x7f0000000080)='/proc/self/exe\x00', 0x0, 0x0) close(r0) pipe2(&(0x7f0000000140)={0xffffffffffffffff, <r1=>0xffffffffffffffff}, 0x800) mount$9p_fd(0x0, &(0x7f0000000040)='./file0\x00', &(0x7f00000000c0), 0x408, &(0x7f0000000280)={'trans=fd,', {'rfdno', 0x3d, r0}, 0x2c, {'wfdno', 0x3d, r1}, 0x2c, {[{@cache_loose}, {@mmap}, {@loose}, {@loose}, {@mmap}], [{@mask={'mask', 0x3d, '^MAY_EXEC'}}, {@fsmagic={'fsmagic', 0x3d, 0x10001}}, {@dont_hash}]}})

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Sample report:

Detalles técnicos trazas, registros y código del informe original

==================================================================
BUG: KASAN: use-after-free in kernfs_type include/linux/kernfs.h:335 [inline]
BUG: KASAN: use-after-free in kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline]
BUG: KASAN: use-after-free in __kernfs_remove.part.0+0x843/0x960 fs/kernfs/dir.c:1369
Read of size 2 at addr ffff8880088807f0 by task syz-executor.2/857

CPU: 0 PID: 857 Comm: syz-executor.2 Not tainted 6.0.0-rc3-00363-g7726d4c3e60b #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x6e/0x91 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:317 [inline]
 print_report.cold+0x5e/0x5e5 mm/kasan/report.c:433
 kasan_report+0xa3/0x130 mm/kasan/report.c:495
 kernfs_type include/linux/kernfs.h:335 [inline]
 kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline]
 __kernfs_remove.part.0+0x843/0x960 fs/kernfs/dir.c:1369
 __kernfs_remove fs/kernfs/dir.c:1356 [inline]
 kernfs_remove_by_name_ns+0x108/0x190 fs/kernfs/dir.c:1589
 sysfs_slab_add+0x133/0x1e0 mm/slub.c:5943
 __kmem_cache_create+0x3e0/0x550 mm/slub.c:4899
 create_cache mm/slab_common.c:229 [inline]
 kmem_cache_create_usercopy+0x167/0x2a0 mm/slab_common.c:335
 p9_client_create+0xd4d/0x1190 net/9p/client.c:993
 v9fs_session_init+0x1e6/0x13c0 fs/9p/v9fs.c:408
 v9fs_mount+0xb9/0xbd0 fs/9p/vfs_super.c:126
 legacy_get_tree+0xf1/0x200 fs/fs_context.c:610
 vfs_get_tree+0x85/0x2e0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x675/0x1d00 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x282/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f725f983aed
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f725f0f7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f725faa3f80 RCX: 00007f725f983aed
RDX: 00000000200000c0 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 00007f725f9f419c R08: 0000000020000280 R09: 0000000000000000
R10: 0000000000000408 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000006 R14: 00007f725faa3f80 R15: 00007f725f0d7000
 </TASK>

Allocated by task 855:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:437 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:470
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:7
---truncated---

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.16%
Percentil entre todas las CVEs puntuadas: 5
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1059 Command and Scripting Interpreterexecution60 %

CWE-416 (use-after-free) en kernfs del kernel Linux con AV:L/PR:L permite escalada de privilegios local. La pista sugiere ejecución; el UAF podría permitir ejecutar código en contexto privilegiado.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Behavior Prevention on Endpoint

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-416

Referencias

JSON original (NVD)

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{
  "id": "CVE-2022-50432",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
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          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
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              "lessThan": "3.14",
              "versionType": "semver"
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              "versionType": "semver",
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            },
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              "version": "4.14.298",
              "versionType": "semver",
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            },
            {
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              "version": "4.19.264",
              "versionType": "semver",
              "lessThanOrEqual": "4.19.*"
            },
            {
              "status": "unaffected",
              "version": "5.4.223",
              "versionType": "semver",
              "lessThanOrEqual": "5.4.*"
            },
            {
              "status": "unaffected",
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            },
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              "versionType": "semver",
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            },
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              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/kernfs/dir.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
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  "published": "2025-10-01T12:15:34.977",
  "references": [
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      "url": "https://git.kernel.org/stable/c/028cf780743eea79abffa7206b9dcfc080ad3546",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/02eb35131050735332658029082f61515b7dfe38",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4abc99652812a2ddf932f137515d5c5a04723538",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "url": "https://git.kernel.org/stable/c/af1b57cc39beca203559576b3046094fc9e5eb32",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkernfs: fix use-after-free in __kernfs_remove\n\nSyzkaller managed to trigger concurrent calls to\nkernfs_remove_by_name_ns() for the same file resulting in\na KASAN detected use-after-free. The race occurs when the root\nnode is freed during kernfs_drain().\n\nTo prevent this acquire an additional reference for the root\nof the tree that is removed before calling __kernfs_remove().\n\nFound by syzkaller with the following reproducer (slab_nomerge is\nrequired):\n\nsyz_mount_image$ext4(0x0, &(0x7f0000000100)='./file0\\x00', 0x100000, 0x0, 0x0, 0x0, 0x0)\nr0 = openat(0xffffffffffffff9c, &(0x7f0000000080)='/proc/self/exe\\x00', 0x0, 0x0)\nclose(r0)\npipe2(&(0x7f0000000140)={0xffffffffffffffff, <r1=>0xffffffffffffffff}, 0x800)\nmount$9p_fd(0x0, &(0x7f0000000040)='./file0\\x00', &(0x7f00000000c0), 0x408, &(0x7f0000000280)={'trans=fd,', {'rfdno', 0x3d, r0}, 0x2c, {'wfdno', 0x3d, r1}, 0x2c, {[{@cache_loose}, {@mmap}, {@loose}, {@loose}, {@mmap}], [{@mask={'mask', 0x3d, '^MAY_EXEC'}}, {@fsmagic={'fsmagic', 0x3d, 0x10001}}, {@dont_hash}]}})\n\nSample report:\n\n==================================================================\nBUG: KASAN: use-after-free in kernfs_type include/linux/kernfs.h:335 [inline]\nBUG: KASAN: use-after-free in kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline]\nBUG: KASAN: use-after-free in __kernfs_remove.part.0+0x843/0x960 fs/kernfs/dir.c:1369\nRead of size 2 at addr ffff8880088807f0 by task syz-executor.2/857\n\nCPU: 0 PID: 857 Comm: syz-executor.2 Not tainted 6.0.0-rc3-00363-g7726d4c3e60b #5\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014\nCall Trace:\n <TASK>\n __dump_stack lib/dump_stack.c:88 [inline]\n dump_stack_lvl+0x6e/0x91 lib/dump_stack.c:106\n print_address_description mm/kasan/report.c:317 [inline]\n print_report.cold+0x5e/0x5e5 mm/kasan/report.c:433\n kasan_report+0xa3/0x130 mm/kasan/report.c:495\n kernfs_type include/linux/kernfs.h:335 [inline]\n kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline]\n __kernfs_remove.part.0+0x843/0x960 fs/kernfs/dir.c:1369\n __kernfs_remove fs/kernfs/dir.c:1356 [inline]\n kernfs_remove_by_name_ns+0x108/0x190 fs/kernfs/dir.c:1589\n sysfs_slab_add+0x133/0x1e0 mm/slub.c:5943\n __kmem_cache_create+0x3e0/0x550 mm/slub.c:4899\n create_cache mm/slab_common.c:229 [inline]\n kmem_cache_create_usercopy+0x167/0x2a0 mm/slab_common.c:335\n p9_client_create+0xd4d/0x1190 net/9p/client.c:993\n v9fs_session_init+0x1e6/0x13c0 fs/9p/v9fs.c:408\n v9fs_mount+0xb9/0xbd0 fs/9p/vfs_super.c:126\n legacy_get_tree+0xf1/0x200 fs/fs_context.c:610\n vfs_get_tree+0x85/0x2e0 fs/super.c:1530\n do_new_mount fs/namespace.c:3040 [inline]\n path_mount+0x675/0x1d00 fs/namespace.c:3370\n do_mount fs/namespace.c:3383 [inline]\n __do_sys_mount fs/namespace.c:3591 [inline]\n __se_sys_mount fs/namespace.c:3568 [inline]\n __x64_sys_mount+0x282/0x300 fs/namespace.c:3568\n do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\nRIP: 0033:0x7f725f983aed\nCode: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007f725f0f7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5\nRAX: ffffffffffffffda RBX: 00007f725faa3f80 RCX: 00007f725f983aed\nRDX: 00000000200000c0 RSI: 0000000020000040 RDI: 0000000000000000\nRBP: 00007f725f9f419c R08: 0000000020000280 R09: 0000000000000000\nR10: 0000000000000408 R11: 0000000000000246 R12: 0000000000000000\nR13: 0000000000000006 R14: 00007f725faa3f80 R15: 00007f725f0d7000\n </TASK>\n\nAllocated by task 855:\n kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38\n kasan_set_track mm/kasan/common.c:45 [inline]\n set_alloc_info mm/kasan/common.c:437 [inline]\n __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:470\n kasan_slab_alloc include/linux/kasan.h:224 [inline]\n slab_post_alloc_hook mm/slab.h:7\n---truncated---"
    }
  ],
  "lastModified": "2026-08-04T10:18:16.603",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "37026F01-AFEE-47AC-B31E-05AD5F5200BD",
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              "vulnerable": true,
              "matchCriteriaId": "65D387F0-209C-4EAD-98BA-C4B430A840C9",
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          "operator": "OR"
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}