CVE-2026-74504 (GCVE-0-2026-74504)

Vulnerability from cvelistv5 – Published: 2026-08-15 12:27 – Updated: 2026-08-17 05:20
VLAI
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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 37745918e0e7575bc40f38da93a99b9fa6406224 , < d0e19932875746118e298b4c974f3b2d4aeb16fc (git)
Affected: 37745918e0e7575bc40f38da93a99b9fa6406224 , < 5260e195c53e898a4a76527d4bb2178f31795e78 (git)
Affected: 37745918e0e7575bc40f38da93a99b9fa6406224 , < 42c6543ff27ea280334244458d4f52ec7133cc05 (git)
Affected: 37745918e0e7575bc40f38da93a99b9fa6406224 , < 21e19688433452dfbbbe6b2bb670dea6eb92f0f6 (git)
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Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.103 , ≤ 6.12.* (semver)
Unaffected: 6.18.44 , ≤ 6.18.* (semver)
Unaffected: 7.1.8 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/core/seq/seq_timer.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: Fix division by zero in initialize_timer()\n\nA userspace-driven ALSA timer (SND_UTIMER) lets an unprivileged user set\nthe backing snd_timer\u0027s hardware resolution to an arbitrary 64-bit value\nvia SNDRV_TIMER_IOCTL_CREATE. snd_utimer_create() only rejects zero.\n\nWhen such a timer is bound to a sequencer queue, initialize_timer()\ncomputes the tick period as\n\n\ttmr-\u003eticks = 1000000000 / (r * freq);\n\nwhere r is that user-controlled resolution and freq is the sequencer\nupdate rate in Hz, clamped to MIN_FREQUENCY..MAX_FREQUENCY (10..6250).\nA resolution of 2^63 makes the 64-bit product r * freq wrap to zero for\nany even freq, including DEFAULT_FREQUENCY (1000), so the division faults\nwith a divide-by-zero.\n\nThe division runs under tmr-\u003elock with interrupts disabled, so the oops\nleaves the spinlock held and hangs the CPU. It is reachable by an\nunprivileged user with access to /dev/snd/timer and /dev/snd/seq.\n\n  Oops: divide error: 0000 [#1] SMP KASAN PTI\n  CPU: 7 UID: 1000 PID: 456 Comm: alsa_seq_utimer Not tainted 7.2.0-rc4+\n  RIP: 0010:initialize_timer.constprop.0+0x20a/0x2d0\n   snd_seq_timer_start+0x15e/0x2b0\n   snd_seq_control_queue+0x56f/0xba0\n   snd_seq_write+0x3e0/0x730\n\nReject an overflowing product with check_mul_overflow() and fall back to\na single tick, which also avoids feeding a wrapped-but-nonzero divisor\n(e.g. 2^63 * 1000 mod 2^64 == 0, or other resolutions wrapping to a small\nvalue) into the period computation."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:20:43.047Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/d0e19932875746118e298b4c974f3b2d4aeb16fc"
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        {
          "url": "https://git.kernel.org/stable/c/5260e195c53e898a4a76527d4bb2178f31795e78"
        },
        {
          "url": "https://git.kernel.org/stable/c/42c6543ff27ea280334244458d4f52ec7133cc05"
        },
        {
          "url": "https://git.kernel.org/stable/c/21e19688433452dfbbbe6b2bb670dea6eb92f0f6"
        }
      ],
      "title": "ALSA: seq: Fix division by zero in initialize_timer()",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74504",
    "datePublished": "2026-08-15T12:27:28.829Z",
    "dateReserved": "2026-08-15T05:44:03.908Z",
    "dateUpdated": "2026-08-17T05:20:43.047Z",
    "state": "PUBLISHED"
  },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-21T07:32:42+00:00",
      "cve": "CVE-2026-74504",
      "id": "CVE-2026-74504",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ALSA: seq: Fix division by zero in initialize_timer()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74504.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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