CVE-2021-47509: ALSA: pcm: oss: Limit the period size to 16MB

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-24 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: oss: Limit the period size to 16MB Set the practical limit to the period size (the fragment shift in OSS) instead of a full 31bit; a too large value could lead to the exhaust of memory as we allocate temporary buffers of the period size, too. As of this patch, we set to 16MB limit, which should cover all use cases.

Affected products

Linux kernel: before 4.4.295; from 4.5 before 4.9.293; from 4.10 before 4.14.258; from 4.15 before 4.19.221; from 4.20 before 5.4.165; from 5.5 before 5.10.85 — fixed in 4.14.258, 4.19.221, 4.4.295, 4.9.293, 5.10.85, 5.15.8

How to fix

Upgrade to a fixed version: Linux kernel 4.14.258, 4.19.221, 4.4.295, 4.9.293. Check the vendor advisory for mitigations.

References

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