{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.4-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  tracing: Fix NULL pointer dereference in func_set_flag()  func_set_flag() dereferences tr-\u003ecurrent_trace_flags before verifying that the current tracer is actually the function tracer. When the active tracer has been switched away from \"function\" (e.g., to \"wakeup_rt\"), tr-\u003ecurrent_trace_flags can be NULL, leading to a NULL pointer dereference and kernel crash.  The call chain that triggers this is:    trace_options_write()     -\u003e __set_tracer_option()       -\u003e trace-\u003eset_flag()          /* func_set_flag */  In func_set_flag(), the first operation is:    if (!!set == !!(tr-\u003ecurrent_trace_flags-\u003eval \u0026 bit))  This dereferences tr-\u003ecurrent_trace_flags unconditionally. The safety check that guards against a non-function tracer:    if (tr-\u003ecurrent_trace != \u0026function_trace)       return 0;  is placed *after* the dereference, which is too late.  This was observed with the following crash dump:    BUG: unable to handle page fault at 0000000000000000   RIP: func_set_flag+0xd    Call Trace:    __set_tracer_option+0x27    trace_options_write+0x75    vfs_write+0x12a    ksys_write+0x66    do_syscall_64+0x5b    RIP: ffffffff914c973d  RSP: ff67ec88b01dfdf0  RFLAGS: 00010202   RAX: 0000000000000000  RBX: ff3a826e80354580  RCX: 0000000000000001   RDX: 0000000000000001  RSI: 0000000000000000  RDI: ffffffff93918080  The disassembly confirms the fault:    func_set_flag+0:   mov 0x1f08(%rdi), %rax  ; RAX = tr-\u003ecurrent_trace_flags = NULL   func_set_flag+13:  mov (%rax), %eax        ; page fault: dereference NULL  At the time of the crash:   tr-\u003ecurrent_trace_flags = 0x0 (NULL)   tr-\u003ecurrent_trace = wakeup_rt_tracer (not function_trace)  The scenario is that a process opens a function tracer option file (such as \"func_stack_trace\"), then the current tracer is switched to another tracer (e.g., \"wakeup_rt\"), which sets current_trace_flags to NULL. When the process subsequently writes to the option file, func_set_flag() is invoked and crashes on the NULL dereference.  Fix this by moving the current_trace check before the current_trace_flags dereference, so that func_set_flag() returns early when the function tracer is not active.",
  "id": "DEBIAN-CVE-2026-64451",
  "modified": "2026-09-14T16:47:40.961885220Z",
  "published": "2026-07-25T10:17:30.013Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64451"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64451"
  ]
}