CVE-2025-21704 Information

Description

In the Linux kernel the following vulnerability has been resolved:

usb: cdc-acm: Check control transfer buffer size before access

If the first fragment is shorter than struct usb_cdc_notification we can’t calculate an expected_size. Log an error and discard the notification instead of reading lengths from memory outside the received data which can lead to memory corruption when the expected_size decreases between fragments causing expected_size - acm->nb_index to wrap.

This issue has been present since the beginning of git history; however it only leads to memory corruption since commit ea2583529cd1 (## Reference https://git.kernel.org/stable/c/383d516a0ebc8641372b521c8cb717f0f1834831 https://git.kernel.org/stable/c/6abb510251e75f875797d8983a830e6731fa281c https://git.kernel.org/stable/c/7828e9363ac4d23b02419bf2a45b9f1d9fb35646 https://git.kernel.org/stable/c/e563b01208f4d1f609bcab13333b6c0e24ce6a01 https://git.kernel.org/stable/c/f64079bef6a8a7823358c3f352ea29a617844636