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CVE-2023-53685

Estado: AnalizadaMedia (5.5)—

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

tun: Fix memory leak for detached NAPI queue.

syzkaller reported [0] memory leaks of sk and skb related to the TUN device with no repro, but we can reproduce it easily with:

If we enable NAPI and multi-queue on a TUN device, we can put skb into tfile->sk.sk_write_queue after the queue is detached. We should prevent it by checking tfile->detached before queuing skb.

Note this must be done under tfile->sk.sk_write_queue.lock because write() and ioctl(IFF_DETACH_QUEUE) can run concurrently. Otherwise, there would be a small race window:

Leer descripción completaMostrar menos

Another solution is to call tun_queue_purge() when closing and reattaching the detached queue, but it could paper over another problems. Also, we do the same kind of test for IFF_NAPI_FRAGS.

Detalles técnicos trazas, registros y código del informe original
  struct ifreq ifr = {}
  int fd_tun, fd_tmp;
  char buf[4] = {};

  fd_tun = openat(AT_FDCWD, "/dev/net/tun", O_WRONLY, 0);
  ifr.ifr_flags = IFF_TUN | IFF_NAPI | IFF_MULTI_QUEUE;
  ioctl(fd_tun, TUNSETIFF, &ifr);

  ifr.ifr_flags = IFF_DETACH_QUEUE;
  ioctl(fd_tun, TUNSETQUEUE, &ifr);

  fd_tmp = socket(AF_PACKET, SOCK_PACKET, 0);
  ifr.ifr_flags = IFF_UP;
  ioctl(fd_tmp, SIOCSIFFLAGS, &ifr);

  write(fd_tun, buf, sizeof(buf));
  close(fd_tun);

  write()                             ioctl(IFF_DETACH_QUEUE)
  `- tun_get_user                     `- __tun_detach
     |- if (tfile->detached)             |- tun_disable_queue
     |  `-> false                        |  `- tfile->detached = tun
     |                                   `- tun_queue_purge
     |- spin_lock_bh(&queue->lock)
     `- __skb_queue_tail(queue, skb)

[0]:
unreferenced object 0xffff88801edbc800 (size 2048):
  comm "syz-executor.1", pid 33269, jiffies 4295743834 (age 18.756s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............
  backtrace:
    [<000000008c16ea3d>] __do_kmalloc_node mm/slab_common.c:965 [inline]
    [<000000008c16ea3d>] __kmalloc+0x4a/0x130 mm/slab_common.c:979
    [<000000003addde56>] kmalloc include/linux/slab.h:563 [inline]
    [<000000003addde56>] sk_prot_alloc+0xef/0x1b0 net/core/sock.c:2035
    [<000000003e20621f>] sk_alloc+0x36/0x2f0 net/core/sock.c:2088
    [<0000000028e43843>] tun_chr_open+0x3d/0x190 drivers/net/tun.c:3438
    [<000000001b0f1f28>] misc_open+0x1a6/0x1f0 drivers/char/misc.c:165
    [<000000004376f706>] chrdev_open+0x111/0x300 fs/char_dev.c:414
    [<00000000614d379f>] do_dentry_open+0x2f9/0x750 fs/open.c:920
    [<000000008eb24774>] do_open fs/namei.c:3636 [inline]
    [<000000008eb24774>] path_openat+0x143f/0x1a30 fs/namei.c:3791
    [<00000000955077b5>] do_filp_open+0xce/0x1c0 fs/namei.c:3818
    [<00000000b78973b0>] do_sys_openat2+0xf0/0x260 fs/open.c:1356
    [<00000000057be699>] do_sys_open fs/open.c:1372 [inline]
    [<00000000057be699>] __do_sys_openat fs/open.c:1388 [inline]
    [<00000000057be699>] __se_sys_openat fs/open.c:1383 [inline]
    [<00000000057be699>] __x64_sys_openat+0x83/0xf0 fs/open.c:1383
    [<00000000a7d2182d>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<00000000a7d2182d>] do_syscall_64+0x3c/0x90 arch/x86/entry/common.c:80
    [<000000004cc4e8c4>] entry_SYSCALL_64_after_hwframe+0x72/0xdc

unreferenced object 0xffff88802f671700 (size 240):
  comm "syz-executor.1", pid 33269, jiffies 4295743854 (age 18.736s)
  hex dump (first 32 bytes):
    68 c9 db 1e 80 88 ff ff 68 c9 db 1e 80 88 ff ff  h.......h.......
    00 c0 7b 2f 80 88 ff ff 00 c8 db 1e 80 88 ff ff  ..{/............
  backtrace:
    [<00000000e9d9fdb6>] __alloc_skb+0x223/0x250 net/core/skbuff.c:644
    [<000000002c3e4e0b>] alloc_skb include/linux/skbuff.h:1288 [inline]
    [<000000002c3e4e0b>] alloc_skb_with_frags+0x6f/0x350 net/core/skbuff.c:6378
    [<00000000825f98d7>] sock_alloc_send_pskb+0x3ac/0x3e0 net/core/sock.c:2729
    [<00000000e9eb3df3>] tun_alloc_skb drivers/net/tun.c:1529 [inline]
    [<
---truncated---

CVSS

Probabilidad de explotación (EPSS)

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).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2023-53685",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "cde8b15f1aabe327038ee4e0e11dd6b798572f69",
              "lessThan": "9cae243b9ae25adfe468cd47ceca591f6725b79c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "cde8b15f1aabe327038ee4e0e11dd6b798572f69",
              "lessThan": "0d20210a190f76db9ec35ee4e0fc77e6c7a148f5",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "cde8b15f1aabe327038ee4e0e11dd6b798572f69",
              "lessThan": "82b2bc279467c875ec36f8ef820f00997c2a4e8e",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "drivers/net/tun.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.8"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "3.8",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.1.30",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.3.4",
              "versionType": "semver",
              "lessThanOrEqual": "6.3.*"
            },
            {
              "status": "unaffected",
              "version": "6.4",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/net/tun.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-10-07T16:15:52.777",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0d20210a190f76db9ec35ee4e0fc77e6c7a148f5",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/82b2bc279467c875ec36f8ef820f00997c2a4e8e",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9cae243b9ae25adfe468cd47ceca591f6725b79c",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntun: Fix memory leak for detached NAPI queue.\n\nsyzkaller reported [0] memory leaks of sk and skb related to the TUN\ndevice with no repro, but we can reproduce it easily with:\n\n  struct ifreq ifr = {}\n  int fd_tun, fd_tmp;\n  char buf[4] = {};\n\n  fd_tun = openat(AT_FDCWD, \"/dev/net/tun\", O_WRONLY, 0);\n  ifr.ifr_flags = IFF_TUN | IFF_NAPI | IFF_MULTI_QUEUE;\n  ioctl(fd_tun, TUNSETIFF, &ifr);\n\n  ifr.ifr_flags = IFF_DETACH_QUEUE;\n  ioctl(fd_tun, TUNSETQUEUE, &ifr);\n\n  fd_tmp = socket(AF_PACKET, SOCK_PACKET, 0);\n  ifr.ifr_flags = IFF_UP;\n  ioctl(fd_tmp, SIOCSIFFLAGS, &ifr);\n\n  write(fd_tun, buf, sizeof(buf));\n  close(fd_tun);\n\nIf we enable NAPI and multi-queue on a TUN device, we can put skb into\ntfile->sk.sk_write_queue after the queue is detached.  We should prevent\nit by checking tfile->detached before queuing skb.\n\nNote this must be done under tfile->sk.sk_write_queue.lock because write()\nand ioctl(IFF_DETACH_QUEUE) can run concurrently.  Otherwise, there would\nbe a small race window:\n\n  write()                             ioctl(IFF_DETACH_QUEUE)\n  `- tun_get_user                     `- __tun_detach\n     |- if (tfile->detached)             |- tun_disable_queue\n     |  `-> false                        |  `- tfile->detached = tun\n     |                                   `- tun_queue_purge\n     |- spin_lock_bh(&queue->lock)\n     `- __skb_queue_tail(queue, skb)\n\nAnother solution is to call tun_queue_purge() when closing and\nreattaching the detached queue, but it could paper over another\nproblems.  Also, we do the same kind of test for IFF_NAPI_FRAGS.\n\n[0]:\nunreferenced object 0xffff88801edbc800 (size 2048):\n  comm \"syz-executor.1\", pid 33269, jiffies 4295743834 (age 18.756s)\n  hex dump (first 32 bytes):\n    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................\n    00 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............\n  backtrace:\n    [<000000008c16ea3d>] __do_kmalloc_node mm/slab_common.c:965 [inline]\n    [<000000008c16ea3d>] __kmalloc+0x4a/0x130 mm/slab_common.c:979\n    [<000000003addde56>] kmalloc include/linux/slab.h:563 [inline]\n    [<000000003addde56>] sk_prot_alloc+0xef/0x1b0 net/core/sock.c:2035\n    [<000000003e20621f>] sk_alloc+0x36/0x2f0 net/core/sock.c:2088\n    [<0000000028e43843>] tun_chr_open+0x3d/0x190 drivers/net/tun.c:3438\n    [<000000001b0f1f28>] misc_open+0x1a6/0x1f0 drivers/char/misc.c:165\n    [<000000004376f706>] chrdev_open+0x111/0x300 fs/char_dev.c:414\n    [<00000000614d379f>] do_dentry_open+0x2f9/0x750 fs/open.c:920\n    [<000000008eb24774>] do_open fs/namei.c:3636 [inline]\n    [<000000008eb24774>] path_openat+0x143f/0x1a30 fs/namei.c:3791\n    [<00000000955077b5>] do_filp_open+0xce/0x1c0 fs/namei.c:3818\n    [<00000000b78973b0>] do_sys_openat2+0xf0/0x260 fs/open.c:1356\n    [<00000000057be699>] do_sys_open fs/open.c:1372 [inline]\n    [<00000000057be699>] __do_sys_openat fs/open.c:1388 [inline]\n    [<00000000057be699>] __se_sys_openat fs/open.c:1383 [inline]\n    [<00000000057be699>] __x64_sys_openat+0x83/0xf0 fs/open.c:1383\n    [<00000000a7d2182d>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n    [<00000000a7d2182d>] do_syscall_64+0x3c/0x90 arch/x86/entry/common.c:80\n    [<000000004cc4e8c4>] entry_SYSCALL_64_after_hwframe+0x72/0xdc\n\nunreferenced object 0xffff88802f671700 (size 240):\n  comm \"syz-executor.1\", pid 33269, jiffies 4295743854 (age 18.736s)\n  hex dump (first 32 bytes):\n    68 c9 db 1e 80 88 ff ff 68 c9 db 1e 80 88 ff ff  h.......h.......\n    00 c0 7b 2f 80 88 ff ff 00 c8 db 1e 80 88 ff ff  ..{/............\n  backtrace:\n    [<00000000e9d9fdb6>] __alloc_skb+0x223/0x250 net/core/skbuff.c:644\n    [<000000002c3e4e0b>] alloc_skb include/linux/skbuff.h:1288 [inline]\n    [<000000002c3e4e0b>] alloc_skb_with_frags+0x6f/0x350 net/core/skbuff.c:6378\n    [<00000000825f98d7>] sock_alloc_send_pskb+0x3ac/0x3e0 net/core/sock.c:2729\n    [<00000000e9eb3df3>] tun_alloc_skb drivers/net/tun.c:1529 [inline]\n    [<\n---truncated---"
    }
  ],
  "lastModified": "2026-06-17T06:45:52.700",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "7074C173-6A8B-481E-B785-34D225F31DAE",
              "versionEndExcluding": "6.1.30",
              "versionStartIncluding": "3.8"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "26C54BF0-3EED-46D4-92A7-5F07F658B49B",
              "versionEndExcluding": "6.3.4",
              "versionStartIncluding": "6.2"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.4:rc1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "38BC6744-7D25-4C02-9966-B224CD071D30"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.4:rc2:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "76061B41-CAE9-4467-BEDE-0FFC7956F2A1"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}