{"id":"CVE-2026-74504","summary":"ALSA: seq: Fix division by zero in initialize_timer()","details":"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's 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.","modified":"2026-08-18T03:30:57.981880632Z","published":"2026-08-15T12:27:28.829Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74504.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/21e19688433452dfbbbe6b2bb670dea6eb92f0f6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/42c6543ff27ea280334244458d4f52ec7133cc05"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5260e195c53e898a4a76527d4bb2178f31795e78"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d0e19932875746118e298b4c974f3b2d4aeb16fc"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74504.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74504"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"37745918e0e7575bc40f38da93a99b9fa6406224"},{"fixed":"d0e19932875746118e298b4c974f3b2d4aeb16fc"},{"fixed":"5260e195c53e898a4a76527d4bb2178f31795e78"},{"fixed":"42c6543ff27ea280334244458d4f52ec7133cc05"},{"fixed":"21e19688433452dfbbbe6b2bb670dea6eb92f0f6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74504.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.12.0"},{"fixed":"6.12.103"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.44"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74504.json"}}],"schema_version":"1.9.0"}