CVE-2026-93167 (GCVE-0-2026-93167)
Vulnerability from cvelistv5
Published
2026-09-17 16:11
Modified
2026-10-19 09:06
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: csky: Fix a4/a5 restoration in syscall trace path The syscall trace path reloads syscall arguments from pt_regs before calling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall arguments are prepared as stack arguments before invoking syscallid. The current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since those offsets are relative to the original pt_regs base, loading them after changing sp fetches the wrong slots. As a result, traced syscalls that use the 5th or 6th argument may receive corrupted arguments. This is visible with mmap2(), which takes six arguments. A small PTRACE_SYSCALL reproducer opens a file and maps one page with: mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0) Before the fix, the traced child fails the mmap and exits with 12. After the fix, the mapping succeeds and the child exits with 0. Fix the trace path by loading a4/a5 from pt_regs before changing sp. Tested on: ck860f, linux-4.19.15, C-SKY abiv2
References
Impacted products
Vendor Product Version
Linux Linux Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: e0bbb53843b5fdfe464b099217e3b9d97e8a75d7
Version: 108681048cf728a8570e036c34ebd7daa43133b4
Version: 3a5837c692918c229baf63fe7950965d27c48ac2
Version: 5.4.47   ≤
Version: 5.6.19   ≤
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncsky: Fix a4/a5 restoration in syscall trace path\n\nThe syscall trace path reloads syscall arguments from pt_regs before\ncalling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall\narguments are prepared as stack arguments before invoking syscallid.\n\nThe current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since\nthose offsets are relative to the original pt_regs base, loading them\nafter changing sp fetches the wrong slots. As a result, traced syscalls\nthat use the 5th or 6th argument may receive corrupted arguments.\n\nThis is visible with mmap2(), which takes six arguments. A small\nPTRACE_SYSCALL reproducer opens a file and maps one page with:\n\n  mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0)\n\nBefore the fix, the traced child fails the mmap and exits with 12.\nAfter the fix, the mapping succeeds and the child exits with 0.\n\nFix the trace path by loading a4/a5 from pt_regs before changing sp.\n\nTested on: ck860f, linux-4.19.15, C-SKY abiv2"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:06:39.063Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e9ae8e86eed68bea5d2670eadf61938a43bd2263"
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        {
          "url": "https://git.kernel.org/stable/c/64e3ec7a71d3b715e2567f19f64207f04999bb0c"
        },
        {
          "url": "https://git.kernel.org/stable/c/863fa63fd1491f201ac819f805a8db98d2a32c3d"
        },
        {
          "url": "https://git.kernel.org/stable/c/e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212e"
        },
        {
          "url": "https://git.kernel.org/stable/c/31c81b376e5f058c7f2c94f69719cf7caec2fc3f"
        },
        {
          "url": "https://git.kernel.org/stable/c/a776afa89424570bfa637ebf812ca281a5732904"
        },
        {
          "url": "https://git.kernel.org/stable/c/343aa5275484d627c921a42e8e115cae366be5de"
        },
        {
          "url": "https://git.kernel.org/stable/c/abb81e5ce7d995baa41556b8125fa59e28ba3be8"
        }
      ],
      "title": "csky: Fix a4/a5 restoration in syscall trace path",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93167",
    "datePublished": "2026-09-17T16:11:59.234Z",
    "dateReserved": "2026-09-17T16:02:15.090Z",
    "dateUpdated": "2026-10-19T09:06:39.063Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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