CVE-2025-39816

In the Linux kernel, the following vulnerability has been resolved:

io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths

Since the buffers are mapped from userspace, it is prudent to use

READ_ONCE() 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.