bpf: test_run: Fix the null pointer dereference issue in bpf_lwt_xmit_push_encap

{
  "id": "7c68f077a4e777e6c70b4ce83eb30276fc1f112f1230e9999717acbaa9cb53c0",
  "url": "https://osv.dev/vulnerability/CVE-2026-53111",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: test_run: Fix the null pointer dereference issue in bpf_lwt_xmit_push_encap",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: test_run: Fix the null pointer dereference issue in bpf_lwt_xmit_push_encap The bpf_lwt_xmit_push_encap helper needs to access skb_dst(skb)->dev to calculate the needed headroom: err = skb_cow_head(skb, len + LL_RESERVED_SPACE(skb_dst(skb)->dev)); But skb->_skb_refdst may not be initialized when the skb is set up by bpf_prog_test_run_skb function. Executing bpf_lwt_push_ip_encap function in this scenario will trigger null pointer dereference, causing a kernel crash as Yinhao reported: [ 105.186365] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 105.186382] #PF: supervisor read access in kernel mode [ 105.186388] #PF: error_code(0x0000) - not-present page [ 105.186393] PGD 121d3d067 P4D 121d3d067 PUD 106c83067 PMD 0 [ 105.186404] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 105.186412] CPU: 3 PID: 3250 Comm: poc Kdump: loaded Not tainted 6.19.0-rc5 #1 [ 105.186423] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 105.186427] RIP: 0010:bpf_lwt_push_ip_encap+0x1eb/0x520 [ 105.186443] Code: 0f 84 de 01 00 00 0f b7 4a 04 66 85 c9 0f 85 47 01 00 00 31 c0 5b 5d 41 5c 41 5d 41 5e c3 cc cc cc cc 48 8b 73 58 48 83 e6 fe <48> 8b 36 0f b7 be ec 00 00 00 0f b7 b6 e6 00 00 00 01 fe 83 e6 f0 [ 105.186449] RSP: 0018:ffffbb0e0387bc50 EFLAGS: 00010246 [ 105.186455] RAX: 000000000000004e RBX: ffff94c74e036500 RCX: ffff94c74874da00 [ 105.186460] RDX: 0000000000000000 RSI",
    "evidence": "osv:CVE-2026-53111",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.175",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.141",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.91",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.33",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-53111",
      "aliases": [
        "CVE-2026-53111"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "52f278774e796a553be0c869dcaaee6f259ca795"
                },
                {
                  "fixed": "5c8d1f91fc4898d79f29d79c1a6f7c2b3ee66fb0"
                },
                {
                  "fixed": "c7ad31fb948fdd4905263f4324160682c3fa7bc6"
                },
                {
                  "fixed": "599905c3f10bb83e6e6881d5a7f5cea5df07dc23"
                },
                {
                  "fixed": "5500913516e071dbe23e5a404c861dd2d82c9589"
                },
                {
                  "fixed": "94f95328b9070909b5b875c647b17a11d3d85567"
                },
                {
                  "fixed": "972787479ee73006fddb5e59ab5c8e733810ff42"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53111.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.1.0"
                },
                {
                  "fixed": "6.1.175"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.141"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.91"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.33"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.10"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53111.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:46.189683544Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5500913516e071dbe23e5a404c861dd2d82c9589",
        "https://git.kernel.org/stable/c/599905c3f10bb83e6e6881d5a7f5cea5df07dc23",
        "https://git.kernel.org/stable/c/5c8d1f91fc4898d79f29d79c1a6f7c2b3ee66fb0",
        "https://git.kernel.org/stable/c/94f95328b9070909b5b875c647b17a11d3d85567",
        "https://git.kernel.org/stable/c/972787479ee73006fddb5e59ab5c8e733810ff42",
        "https://git.kernel.org/stable/c/c7ad31fb948fdd4905263f4324160682c3fa7bc6",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53111.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-53111",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53111.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-53111",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 513985,
  "published_at": "2026-06-24T16:30:44.691+00:00"
}