ghsa-jgf3-fmmf-vj4h
Vulnerability from github
Published
2024-12-04 15:31
Modified
2024-12-19 21:31
Details

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

bpf: sync_linked_regs() must preserve subreg_def

Range propagation must not affect subreg_def marks, otherwise the following example is rewritten by verifier incorrectly when BPF_F_TEST_RND_HI32 flag is set:

0: call bpf_ktime_get_ns call bpf_ktime_get_ns 1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff 2: w1 = w0 rewrites w1 = w0 3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r) 4: r1 >>= 32 r11 <<= 32 (r) 5: r0 = r1 r1 |= r11 (r) 6: exit; if w0 < 0xa goto pc+0 r1 >>= 32 r0 = r1 exit

(or zero extension of w1 at (2) is missing for architectures that require zero extension for upper register half).

The following happens w/o this patch: - r0 is marked as not a subreg at (0); - w1 is marked as subreg at (2); - w1 subreg_def is overridden at (3) by copy_register_state(); - w1 is read at (5) but mark_insn_zext() does not mark (2) for zero extension, because w1 subreg_def is not set; - because of BPF_F_TEST_RND_HI32 flag verifier inserts random value for hi32 bits of (2) (marked (r)); - this random value is read at (5).

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{
   affected: [],
   aliases: [
      "CVE-2024-53125",
   ],
   database_specific: {
      cwe_ids: [],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-12-04T14:15:20Z",
      severity: null,
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: sync_linked_regs() must preserve subreg_def\n\nRange propagation must not affect subreg_def marks, otherwise the\nfollowing example is rewritten by verifier incorrectly when\nBPF_F_TEST_RND_HI32 flag is set:\n\n  0: call bpf_ktime_get_ns                   call bpf_ktime_get_ns\n  1: r0 &= 0x7fffffff       after verifier   r0 &= 0x7fffffff\n  2: w1 = w0                rewrites         w1 = w0\n  3: if w0 < 10 goto +0     -------------->  r11 = 0x2f5674a6     (r)\n  4: r1 >>= 32                               r11 <<= 32           (r)\n  5: r0 = r1                                 r1 |= r11            (r)\n  6: exit;                                   if w0 < 0xa goto pc+0\n                                             r1 >>= 32\n                                             r0 = r1\n                                             exit\n\n(or zero extension of w1 at (2) is missing for architectures that\n require zero extension for upper register half).\n\nThe following happens w/o this patch:\n- r0 is marked as not a subreg at (0);\n- w1 is marked as subreg at (2);\n- w1 subreg_def is overridden at (3) by copy_register_state();\n- w1 is read at (5) but mark_insn_zext() does not mark (2)\n  for zero extension, because w1 subreg_def is not set;\n- because of BPF_F_TEST_RND_HI32 flag verifier inserts random\n  value for hi32 bits of (2) (marked (r));\n- this random value is read at (5).",
   id: "GHSA-jgf3-fmmf-vj4h",
   modified: "2024-12-19T21:31:10Z",
   published: "2024-12-04T15:31:52Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-53125",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/60fd3538d2a8fd44c41d25088c0ece3e1fd30659",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/b57ac2d92c1f565743f6890a5b9cf317ed856b09",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/bfe9446ea1d95f6cb7848da19dfd58d2eec6fd84",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/dadf82c1b2608727bcc306843b540cd7414055a7",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/e2ef0f317a52e678fe8fa84b94d6a15b466d6ff0",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/e9bd9c498cb0f5843996dbe5cbce7a1836a83c70",
      },
   ],
   schema_version: "1.4.0",
   severity: [],
}


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