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CVE-2025-21852

Estado: ModificadaMedia (5.5)—

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

net: Add rx_skb of kfree_skb to raw_tp_null_args[].

Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0] in trace_kfree_skb if the prog does not check if rx_sk is NULL.

Commit c53795d48ee8 ("net: add rx_sk to trace_kfree_skb") added rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL.

Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier validate such a prog and prevent the issue.

Now we fail to load such a prog:

Note this fix requires commit 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL").

Detalles técnicos trazas, registros y código del informe original
  libbpf: prog 'drop': -- BEGIN PROG LOAD LOG --
  0: R1=ctx() R10=fp0
  ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21
  0: (79) r3 = *(u64 *)(r1 +24)
  func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock'
  1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1)
  ; bpf_printk("sk: %d, %d\n", sk, sk->__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24
  1: (69) r4 = *(u16 *)(r3 +16)
  R3 invalid mem access 'trusted_ptr_or_null_'
  processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
  -- END PROG LOAD LOG --

[0]:
BUG: kernel NULL pointer dereference, address: 0000000000000010
 PF: supervisor read access in kernel mode
 PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
PREEMPT SMP
RIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d
Call Trace:
 <TASK>
 ? __die+0x1f/0x60
 ? page_fault_oops+0x148/0x420
 ? search_bpf_extables+0x5b/0x70
 ? fixup_exception+0x27/0x2c0
 ? exc_page_fault+0x75/0x170
 ? asm_exc_page_fault+0x22/0x30
 ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d
 bpf_trace_run4+0x68/0xd0
 ? unix_stream_connect+0x1f4/0x6f0
 sk_skb_reason_drop+0x90/0x120
 unix_stream_connect+0x1f4/0x6f0
 __sys_connect+0x7f/0xb0
 __x64_sys_connect+0x14/0x20
 do_syscall_64+0x47/0xc30
 entry_SYSCALL_64_after_hwframe+0x4b/0x53

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-2025-21852",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-21852",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-10-01T19:26:08.323491Z"
        }
      }
    ],
    "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
      },
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "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": "c53795d48ee8f385c6a9e394651e7ee914baaeba",
              "lessThan": "f579afacd0a66971fc8481f30d2d377e230a8342",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c53795d48ee8f385c6a9e394651e7ee914baaeba",
              "lessThan": "4dba79c1e7aad6620bbb707b6c4459380fd90860",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c53795d48ee8f385c6a9e394651e7ee914baaeba",
              "lessThan": "5da7e15fb5a12e78de974d8908f348e279922ce9",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "kernel/bpf/btf.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.11"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.11",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.17",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.13.5",
              "versionType": "semver",
              "lessThanOrEqual": "6.13.*"
            },
            {
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "kernel/bpf/btf.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-03-12T10:15:17.927",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/4dba79c1e7aad6620bbb707b6c4459380fd90860",
      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5da7e15fb5a12e78de974d8908f348e279922ce9",
      "tags": [
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      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f579afacd0a66971fc8481f30d2d377e230a8342",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    },
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: Add rx_skb of kfree_skb to raw_tp_null_args[].\n\nYan Zhai reported a BPF prog could trigger a null-ptr-deref [0]\nin trace_kfree_skb if the prog does not check if rx_sk is NULL.\n\nCommit c53795d48ee8 (\"net: add rx_sk to trace_kfree_skb\") added\nrx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL.\n\nLet's add kfree_skb to raw_tp_null_args[] to let the BPF verifier\nvalidate such a prog and prevent the issue.\n\nNow we fail to load such a prog:\n\n  libbpf: prog 'drop': -- BEGIN PROG LOAD LOG --\n  0: R1=ctx() R10=fp0\n  ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21\n  0: (79) r3 = *(u64 *)(r1 +24)\n  func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock'\n  1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1)\n  ; bpf_printk(\"sk: %d, %d\\n\", sk, sk->__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24\n  1: (69) r4 = *(u16 *)(r3 +16)\n  R3 invalid mem access 'trusted_ptr_or_null_'\n  processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\n  -- END PROG LOAD LOG --\n\nNote this fix requires commit 838a10bd2ebf (\"bpf: Augment raw_tp\narguments with PTR_MAYBE_NULL\").\n\n[0]:\nBUG: kernel NULL pointer dereference, address: 0000000000000010\n PF: supervisor read access in kernel mode\n PF: error_code(0x0000) - not-present page\nPGD 0 P4D 0\nPREEMPT SMP\nRIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d\nCall Trace:\n <TASK>\n ? __die+0x1f/0x60\n ? page_fault_oops+0x148/0x420\n ? search_bpf_extables+0x5b/0x70\n ? fixup_exception+0x27/0x2c0\n ? exc_page_fault+0x75/0x170\n ? asm_exc_page_fault+0x22/0x30\n ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d\n bpf_trace_run4+0x68/0xd0\n ? unix_stream_connect+0x1f4/0x6f0\n sk_skb_reason_drop+0x90/0x120\n unix_stream_connect+0x1f4/0x6f0\n __sys_connect+0x7f/0xb0\n __x64_sys_connect+0x14/0x20\n do_syscall_64+0x47/0xc30\n entry_SYSCALL_64_after_hwframe+0x4b/0x53"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net: Add rx_skb of kfree_skb to raw_tp_null_args[]. Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0] in trace_kfree_skb if the prog does not check if rx_sk is NULL. Commit c53795d48ee8 (\"net: add rx_sk to trace_kfree_skb\") added rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL. Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier validate such a prog and prevent the issue. Now we fail to load such a prog: libbpf: prog 'drop': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21 0: (79) r3 = *(u64 *)(r1 +24) func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock' 1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1) ; bpf_printk(\"sk: %d, %d\\n\", sk, sk-&gt;__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24 1: (69) r4 = *(u16 *)(r3 +16) R3 invalid mem access 'trusted_ptr_or_null_' processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 -- END PROG LOAD LOG -- Note this fix requires commit 838a10bd2ebf (\"bpf: Augment raw_tp arguments with PTR_MAYBE_NULL\"). [0]: BUG: kernel NULL pointer dereference, address: 0000000000000010 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 P4D 0 PREEMPT SMP RIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d Call Trace:  ? __die+0x1f/0x60 ? page_fault_oops+0x148/0x420 ? search_bpf_extables+0x5b/0x70 ? fixup_exception+0x27/0x2c0 ? exc_page_fault+0x75/0x170 ? asm_exc_page_fault+0x22/0x30 ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d bpf_trace_run4+0x68/0xd0 ? unix_stream_connect+0x1f4/0x6f0 sk_skb_reason_drop+0x90/0x120 unix_stream_connect+0x1f4/0x6f0 __sys_connect+0x7f/0xb0 __x64_sys_connect+0x14/0x20 do_syscall_64+0x47/0xc30 entry_SYSCALL_64_after_hwframe+0x4b/0x53 "
    }
  ],
  "lastModified": "2026-06-17T08:44:26.773",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "8FC6C994-91D3-44C1-95E0-C930D07CFE85",
              "versionEndExcluding": "6.12.17",
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
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              "versionEndExcluding": "6.13.5",
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*",
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              "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}