CVE-2025-39816: io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths
In the Linux kernel, the following vulnerability has been resolved:
iouring/kbuf: always use READONCE() to read ring provided buffer lengths
Since the buffers are mapped from userspace, it is prudent to use READONCE() to read the value into a local variable, and use that for any other actions taken. Having a stable read of the buffer length avoids worrying about it changing after checking, or being read multiple times.
Similarly, the buffer may well change in between it being picked and being committed. Ensure the looping for incremental ring buffer commit stops if it hits a zero sized buffer, as no further progress can be made at that point.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-39816?
CVE-2025-39816 is classified as a medium severity vulnerability in the Linux kernel.
How do I fix CVE-2025-39816?
To fix CVE-2025-39816, update your Linux kernel to the latest version where this vulnerability has been patched.
What systems are affected by CVE-2025-39816?
CVE-2025-39816 affects the Linux kernel, particularly instances utilizing io_uring APIs.
What are the potential exploits of CVE-2025-39816?
Exploitation of CVE-2025-39816 could lead to unpredictable behavior or system crashes due to improper handling of user-provided buffer lengths.
Is CVE-2025-39816 critical for all versions of the Linux kernel?
CVE-2025-39816 is not critical for all versions but should be assessed on a case-by-case basis for environments using affected kernel versions.