ALSA: seq: Fix division by zero in initialize_timer()
Summary
| CVE | CVE-2026-74504 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-15 13:17:55 UTC |
| Updated | 2026-08-17 06:19:46 UTC |
| Description | 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. |
Risk And Classification
EPSS: 0.001680000 probability, percentile 0.065010000 (date 2026-08-17)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 37745918e0e7575bc40f38da93a99b9fa6406224 d0e19932875746118e298b4c974f3b2d4aeb16fc git | Not specified |
| CNA | Linux | Linux | affected 37745918e0e7575bc40f38da93a99b9fa6406224 5260e195c53e898a4a76527d4bb2178f31795e78 git | Not specified |
| CNA | Linux | Linux | affected 37745918e0e7575bc40f38da93a99b9fa6406224 42c6543ff27ea280334244458d4f52ec7133cc05 git | Not specified |
| CNA | Linux | Linux | affected 37745918e0e7575bc40f38da93a99b9fa6406224 21e19688433452dfbbbe6b2bb670dea6eb92f0f6 git | Not specified |
| CNA | Linux | Linux | affected 6.12 | Not specified |
| CNA | Linux | Linux | unaffected 6.12 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.103 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.44 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.8 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/5260e195c53e898a4a76527d4bb2178f31795e78 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/42c6543ff27ea280334244458d4f52ec7133cc05 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/21e19688433452dfbbbe6b2bb670dea6eb92f0f6 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/d0e19932875746118e298b4c974f3b2d4aeb16fc | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.