CVE-2026-80628

ALSA: seq: oss: Serialize readq reset state with q->lock

Published Aug 28, 2026 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
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

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4904-1 linux-6.12 security update
Ubuntu USN Ubuntu USN USN-8887-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8889-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-2 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9002-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-9003-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9043-1 Linux kernel (NVIDIA) vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-362
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
Weaknesses CWE-362
Type Values Removed Values Added
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
Title ALSA: seq: oss: Serialize readq reset state with q->lock
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 30, 2026, 12:30 PM
Reserved
Aug 26, 2026, 2:34 PM
Status
Received
Published
Aug 28, 2026, 8:16 AM
Modified
Oct 30, 2026, 1:20 PM
Severity
Moderate
Public date
Aug 28, 2026, 12:00 AM