ghsa-q44j-p422-qjh5
Vulnerability from github
Published
2025-08-16 12:30
Modified
2025-08-16 12:30
Details

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

bpf: Reject %p% format string in bprintf-like helpers

static const char fmt[] = "%p%"; bpf_trace_printk(fmt, sizeof(fmt));

The above BPF program isn't rejected and causes a kernel warning at runtime:

Please remove unsupported %\x00 in format string
WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0

This happens because bpf_bprintf_prepare skips over the second %, detected as punctuation, while processing %p. This patch fixes it by not skipping over punctuation. %\x00 is then processed in the next iteration and rejected.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-38528"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-08-16T12:15:28Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject %p% format string in bprintf-like helpers\n\nstatic const char fmt[] = \"%p%\";\n    bpf_trace_printk(fmt, sizeof(fmt));\n\nThe above BPF program isn\u0027t rejected and causes a kernel warning at\nruntime:\n\n    Please remove unsupported %\\x00 in format string\n    WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0\n\nThis happens because bpf_bprintf_prepare skips over the second %,\ndetected as punctuation, while processing %p. This patch fixes it by\nnot skipping over punctuation. %\\x00 is then processed in the next\niteration and rejected.",
  "id": "GHSA-q44j-p422-qjh5",
  "modified": "2025-08-16T12:30:32Z",
  "published": "2025-08-16T12:30:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38528"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c5f5fd47bbda17cb885fe6f03730702cd53d3f8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/61d5fa45ed13e42af14c7e959baba9908b8ee6d4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6952aeace93f8c9ea01849efecac24dd3152c9c9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7be679124bae8cf4fa6e40d7e1661baddfb3289"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f8242745871f81a3ac37f9f51853d12854fd0b58"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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