net/sched: taprio: Limit TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME to INT_MAX.

{
  "id": "2519db6ef31549b854a274c9dd0c87589a13a1be62cf5468569259299a647520",
  "url": "https://osv.dev/vulnerability/CVE-2023-54251",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/sched: taprio: Limit TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME to INT_MAX.",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/sched: taprio: Limit TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME to INT_MAX. syzkaller found zero division error [0] in div_s64_rem() called from get_cycle_time_elapsed(), where sched->cycle_time is the divisor. We have tests in parse_taprio_schedule() so that cycle_time will never be 0, and actually cycle_time is not 0 in get_cycle_time_elapsed(). The problem is that the types of divisor are different; cycle_time is s64, but the argument of div_s64_rem() is s32. syzkaller fed this input and 0x100000000 is cast to s32 to be 0. @TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME={0xc, 0x8, 0x100000000} We use s64 for cycle_time to cast it to ktime_t, so let's keep it and set max for cycle_time. While at it, we prevent overflow in setup_txtime() and add another test in parse_taprio_schedule() to check if cycle_time overflows. Also, we add a new tdc test case for this issue. [0]: divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 1 PID: 103 Comm: kworker/1:3 Not tainted 6.5.0-rc1-00330-g60cc1f7d0605 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:div_s64_rem include/linux/math64.h:42 [inline] RIP: 0010:get_cycle_time_elapsed net/sched/sch_taprio.c:223 [inline] RIP: 0010:find_entry_to_transmit+0x252/0x7e0 net/sched/sch_taprio.c:344 Code: 3c 02 00 0f 85 5e 05 00 00 48 8b 4c 24 08 4d 8b bd 40 01 00 00 48 8b 7c 24 48",
    "evidence": "osv:CVE-2023-54251",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.15.126",
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            "value": "6.1.45",
            "evidence": "/affected/1/ranges"
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          {
            "value": "6.4.10",
            "evidence": "/affected/1/ranges"
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    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-54251",
      "aliases": [
        "CVE-2023-54251"
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            "ecosystem": "Linux"
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      ],
      "modified": "2026-10-28T02:30:40.458817455Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0b45af982a4df0b14fb8669ee2a871cfdfa6a39c",
        "https://git.kernel.org/stable/c/57b3fe08ae06ef11af007b4a182629b12a961e30",
        "https://git.kernel.org/stable/c/e739718444f7bf2fa3d70d101761ad83056ca628",
        "https://git.kernel.org/stable/c/f04f6d9b3b060f7e11219a65a76da65f1489e391",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/54xxx/CVE-2023-54251.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-54251",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
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        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
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  "source_id": "core-osv",
  "document_id": 508203,
  "published_at": "2025-12-30T12:15:48.145+00:00"
}