High [CVE-2026-72262] Fix heap overflow in bytes_ext put/get

In the Linux kernel, the following vulnerability has been resolved: ASoC: SOF: ipc3-control: Fix heap overflow in bytes_ext put/get The ipc_control_data buffer is allocated as kzalloc(max_size), where max_size covers the entire struct sof_ipc_ctrl_data including its flexible array payload.

However, the bounds checks in bytes_ext_put and _bytes_ext_get compared user data lengths against max_size directly, ignoring that cdata->data sits at an offset of sizeof(struct sof_ipc_ctrl_data) bytes into the allocation.

This allowed writing up to sizeof(struct sof_ipc_ctrl_data) bytes past the end of the heap buffer from unprivileged userspace via the ALSA TLV kcontrol interface, and similarly allowed over-reading adjacent heap data on the get path.

Fix all bounds checks to subtract sizeof(*cdata) from max_size so they reflect the actual space available at the cdata->data offset. Also fix the error-path restore in bytes_ext_put which wrote to cdata->data instead of cdata, causing the same overflow.

A flaw was found in the Advanced Linux Sound Architecture (ALSA) Sound Open Firmware (SOF) ipc3-control component of the Linux kernel. This vulnerability, a heap overflow, occurs due to incorrect bounds checks when handling user data lengths.