ALSA: seq: Fix division by zero in initialize_timer()

{
  "id": "5e8f1503bb2cde687b77b8dd179427433b334a198d950834627a7c319ebffd32",
  "url": "https://osv.dev/vulnerability/CVE-2026-74504",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ALSA: seq: Fix division by zero in initialize_timer()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix division by zero in initialize_timer() A userspace-driven ALSA timer (SND_UTIMER) lets an unprivileged user set the backing snd_timer's hardware resolution to an arbitrary 64-bit value via SNDRV_TIMER_IOCTL_CREATE. snd_utimer_create() only rejects zero. When such a timer is bound to a sequencer queue, initialize_timer() computes the tick period as tmr->ticks = 1000000000 / (r * freq); where r is that user-controlled resolution and freq is the sequencer update rate in Hz, clamped to MIN_FREQUENCY..MAX_FREQUENCY (10..6250). A resolution of 2^63 makes the 64-bit product r * freq wrap to zero for any even freq, including DEFAULT_FREQUENCY (1000), so the division faults with a divide-by-zero. The division runs under tmr->lock with interrupts disabled, so the oops leaves the spinlock held and hangs the CPU. It is reachable by an unprivileged user with access to /dev/snd/timer and /dev/snd/seq. Oops: divide error: 0000 [#1] SMP KASAN PTI CPU: 7 UID: 1000 PID: 456 Comm: alsa_seq_utimer Not tainted 7.2.0-rc4+ RIP: 0010:initialize_timer.constprop.0+0x20a/0x2d0 snd_seq_timer_start+0x15e/0x2b0 snd_seq_control_queue+0x56f/0xba0 snd_seq_write+0x3e0/0x730 Reject an overflowing product with check_mul_overflow() and fall back to a single tick, which also avoids feeding a wrapped-but-nonzero divisor (e.g. 2^63 * 1000 mod 2^64 == 0, or other resolutions wrapping to a small value) into the period computation.",
    "evidence": "osv:CVE-2026-74504",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.103",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.44",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-74504",
      "aliases": [
        "CVE-2026-74504"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
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                  "fixed": "5260e195c53e898a4a76527d4bb2178f31795e78"
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                {
                  "fixed": "42c6543ff27ea280334244458d4f52ec7133cc05"
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                {
                  "fixed": "21e19688433452dfbbbe6b2bb670dea6eb92f0f6"
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          "database_specific": {
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        {
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              "type": "ECOSYSTEM",
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              "type": "ECOSYSTEM",
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                  "introduced": "6.13.0"
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                  "fixed": "6.18.44"
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                {
                  "fixed": "7.1.8"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74504.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:20.951887533Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/21e19688433452dfbbbe6b2bb670dea6eb92f0f6",
        "https://git.kernel.org/stable/c/42c6543ff27ea280334244458d4f52ec7133cc05",
        "https://git.kernel.org/stable/c/5260e195c53e898a4a76527d4bb2178f31795e78",
        "https://git.kernel.org/stable/c/d0e19932875746118e298b4c974f3b2d4aeb16fc",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74504.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-74504",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74504.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-74504",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 487315,
  "published_at": "2026-08-15T12:27:28.829+00:00"
}