CVE-2025-40275

/// Technical description

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

ALSA: usb-audio: Fix NULL pointer dereference in snd_usb_mixer_controls_badd

In snd_usb_create_streams(), for UAC version 3 devices, the Interface

Association Descriptor (IAD) is retrieved via usb_ifnum_to_if(). If this

call fails, a fallback routine attempts to obtain the IAD from the next

interface and sets a BADD profile. However, snd_usb_mixer_controls_badd()

assumes that the IAD retrieved from usb_ifnum_to_if() is always valid,

without performing a NULL check. This can lead to a NULL pointer

dereference when usb_ifnum_to_if() fails to find the interface descriptor.

This patch adds a NULL pointer check after calling usb_ifnum_to_if() in

snd_usb_mixer_controls_badd() to prevent the dereference.

This issue was discovered by syzkaller, which triggered the bug by sending

a crafted USB device descriptor.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References