# CVE-2026-80628: ALSA: seq: oss: Serialize readq reset state with q->lock

CVE-2026-80628 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-80628, released August 29, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-80628
- Priority: High
- CVSS: 7.8 (Low)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 28, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80628

## Description

In the Linux kernel, the following vulnerability has been resolved:  ALSA: seq: oss: Serialize readq reset state with q->lock  snd_seq_oss_readq_clear() resets qlen, head, and tail without q->lock even though the normal reader and producer paths serialize the same ring state under that spinlock. A reset can therefore race snd_seq_oss_readq_free() or snd_seq_oss_readq_put_event() and leave stale records in the queue, drop freshly queued ones, or report the wrong readiness after wakeup. KCSAN reports a data race between snd_seq_oss_readq_clear() and snd_seq_oss_readq_free().  Take q->lock while clearing the ring and resetting input_time. Factor the enqueue logic into a caller-locked helper so snd_seq_oss_readq_put_timestamp() updates its suppression state under the same lock instead of racing the reset path.  The buggy scenario involves two paths, with each column showing the order within that path:  reset path:                      locked readq updater: 1. snd_seq_oss_reset() or        1. A reader or callback producer    release reaches                  takes q->lock on the same queue.    snd_seq_oss_readq_clear(). 2. snd_seq_oss_readq_clear()     2. The updater tests or modifies    resets qlen, head, tail,         qlen, head, and tail.    and input_time. 3. snd_seq_oss_readq_clear()     3. The updater completes its    wakes sleepers on                read-modify-write sequence.    q->midi_sleep. 4. Without q->lock, the reset    4. The resulting ring state drives    can overlap the locked           later reads and readiness.    update.  KCSAN reports:  BUG: KCSAN: data-race in snd_seq_oss_readq_clear / snd_seq_oss_readq_free  write to 0xffff8881069fe608 of 4 bytes by task 120516 on cpu 0:   snd_seq_oss_readq_free+0x6c/0x80   snd_seq_oss_read+0xcb/0x250   odev_read+0x38/0x60   vfs_read+0xff/0x600   ksys_read+0xb4/0x140   __x64_sys_read+0x46/0x60   do_syscall_64+0xbb/0x2f0   entry_SYSCALL_64_after_hwframe+0x77/0x7f  read to 0xffff8881069fe608 of 4 bytes by task 120517 on cpu 1:   snd_seq_oss_readq_clear+0x1f/0x90   snd_seq_oss_reset+0xa7/0xf0   snd_seq_oss_ioctl+0x6f6/0x7e0   odev_ioctl+0x56/0xc0   __x64_sys_ioctl+0xd1/0x120   do_syscall_64+0xbb/0x2f0   entry_SYSCALL_64_after_hwframe+0x77/0x7f  value changed: 0x00000001 -> 0x00000000

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-80628](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80628.md) | Aug 29, 2026 |
| Linux | linux Debian 14 | 7.1.5-1 | [DEBIAN-CVE-2026-80628](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80628.md) | Aug 29, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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