{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-53491",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2023-53491"
  ],
  "published": "2025-10-01T11:50:00Z",
  "summary": "start_kernel: Add __no_stack_protector function attribute",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nstart_kernel: Add __no_stack_protector function attribute\n\nBack during the discussion of\ncommit a9a3ed1eff36 (\"x86: Fix early boot crash on gcc-10, third try\")\nwe discussed the need for a function attribute to control the omission\nof stack protectors on a per-function basis; at the time Clang had\nsupport for no_stack_protector but GCC did not. This was fixed in\ngcc-11. Now that the function attribute is available, let's start using\nit.\n\nCallers of boot_init_stack_canary need to use this function attribute\nunless they're compiled with -fno-stack-protector, otherwise the canary\nstored in the stack slot of the caller will differ upon the call to\nboot_init_stack_canary. This will lead to a call to __stack_chk_fail()\nthen panic.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
    }
  ],
  "affected": [
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        "name": "linux"
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        "1:6.1.58-1+rpt2",
        "1:6.1.63-1+rpt1",
        "1:6.1.73-1+rpt1"
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      "ecosystem_specific": {
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-53491"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5a7e8f89cdee16db705905a5b1ce2100b13dd63e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/25e73018b4093e0cfbcec5dc4a4bb86d0b69ed56"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/514ca14ed5444b911de59ed3381dfd195d99fe4b"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-10-03T11:04:09Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.5,
      "cvss_v3_severity": "High",
      "scenario": "AV:N - There is no network-reachable path to this code \u2014 `start_kernel()` and powerpc `start_secondary()` are kernel-initialization and CPU-bring-up entry points invoked from architecture assembly (`head_64.S`, `head_44x.S`, `head_85xx.S`) and from `__cpu_up()` during hotplug/resume, all of which are local to the machine. The vulnerable component is therefore only reachable via local system context (boot, CPU hotplug, suspend/resume).\nAC:L - On a kernel built with `CONFIG_STACKPROTECTOR=y` and a toolchain that instruments these functions, the stale-canary comparison mismatches deterministically on every boot and every secondary-CPU bring-up \u2014 there is no race, no memory-layout dependency, and no timing window to win. The failure reproduces reliably and at will, so no condition beyond the attacker's control gates it.\nPR:N - The panic in `start_kernel()` occurs during kernel initialization, before `init(1)` and before any user account, credential check, or namespace exists; the `start_secondary()` path is likewise entered from the secondary-CPU assembly stub with no privilege gate. No authentication or privilege of any kind is involved in reaching the faulty canary check.\nUI:N - No victim action is needed \u2014 the condition is hit automatically as part of normal boot and CPU bring-up. Nothing must be mounted, opened, or clicked.\nS:U - The `__stack_chk_fail()` \u2192 `panic()` sequence is entirely contained within the kernel's own security authority, affecting only the kernel that executed it. No VM, IOMMU, or sandbox boundary is crossed.\nC:N - `__stack_chk_fail()` is a fail-stop check: it halts the system rather than reading or exposing memory, and no out-of-bounds read, uninitialized data, or attacker-retrievable kernel state is produced. Per the pure-crash guidance, there is no information disclosure.\nI:N - Nothing is written out of bounds and no object is corrupted \u2014 the canary in the caller's frame is intact; the comparison is a false positive caused by the canary *source* changing underneath it. There is no write primitive and no control-flow hijack potential.\nA:H - The outcome is `panic(\"stack-protector: Kernel stack is corrupted in: start_kernel\")`, i.e. an unbootable system, or a panic during secondary-CPU bring-up via `start_secondary()` on hotplug/resume. This is total, unrecoverable loss of availability for the affected machine."
    }
  }
}