{"id":"CVE-2026-80628","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-80628","summary":"ALSA: seq: oss: Serialize readq reset state with q->lock","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: oss: Serialize readq reset state with q->lock\n\nsnd_seq_oss_readq_clear() resets qlen, head, and tail without\nq->lock even though the normal reader and producer paths serialize the\nsame ring state under that spinlock. A reset can therefore race\nsnd_seq_oss_readq_free() or snd_seq_oss_readq_put_event() and leave\nstale records in the queue, drop freshly queued ones, or report the\nwrong readiness after wakeup. KCSAN reports a data race between\nsnd_seq_oss_readq_clear() and snd_seq_oss_readq_free().\n\nTake q->lock while clearing the ring and resetting input_time. Factor\nthe enqueue logic into a caller-locked helper so\nsnd_seq_oss_readq_put_timestamp() updates its suppression state under\nthe same lock instead of racing the reset path.\n\nThe buggy scenario involves two paths, with each column showing the\norder within that path:\n\nreset path:                      locked readq updater:\n1. snd_seq_oss_reset() or        1. A reader or callback producer\n   release reaches                  takes q->lock on the same queue.\n   snd_seq_oss_readq_clear().\n2. snd_seq_oss_readq_clear()     2. The updater tests or modifies\n   resets qlen, head, tail,         qlen, head, and tail.\n   and input_time.\n3. snd_seq_oss_readq_clear()     3. The updater completes its\n   wakes sleepers on                read-modify-write sequence.\n   q->midi_sleep.\n4. Without q->lock, the reset    4. The resulting ring state drives\n   can overlap the locked           later reads and readiness.\n   update.\n\nKCSAN reports:\n\nBUG: KCSAN: data-race in snd_seq_oss_readq_clear /\nsnd_seq_oss_readq_free\n\nwrite to 0xffff8881069fe608 of 4 bytes by task 120516 on cpu 0:\n  snd_seq_oss_readq_free+0x6c/0x80\n  snd_seq_oss_read+0xcb/0x250\n  odev_read+0x38/0x60\n  vfs_read+0xff/0x600\n  ksys_read+0xb4/0x140\n  __x64_sys_read+0x46/0x60\n  do_syscall_64+0xbb/0x2f0\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nread to 0xffff8881069fe608 of 4 bytes by task 120517 on cpu 1:\n  snd_seq_oss_readq_clear+0x1f/0x90\n  snd_seq_oss_reset+0xa7/0xf0\n  snd_seq_oss_ioctl+0x6f6/0x7e0\n  odev_ioctl+0x56/0xc0\n  __x64_sys_ioctl+0xd1/0x120\n  do_syscall_64+0xbb/0x2f0\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nvalue changed: 0x00000001 -> 0x00000000","published":"2026-08-28T06:48:45.377Z","modified":"2026-08-30T03:48:20.985027391Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.18.40"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/287d506d4e0865918cec82bb1361f283a08c979b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/43e10709b1ba288bcbabb9b9cb6e518b2a5d8506"},{"type":"WEB","url":"https://git.kernel.org/stable/c/49ce92d207820f588b0406add82f053decfbe5d9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80628.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80628"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-30T03:48:20.985027391Z"}}