CVE-2026-80969: ALSA: mpu401: Check card index validity at probe
In the Linux kernel, the following vulnerability has been resolved:
ALSA: mpu401: Check card index validity at probe
mpu401 driver blindly trusts that the given devptr->id value is within the proper card index range at probe. It's OK for the devices the driver itself creates at the module probe time, but if the device is bound manually via sysfs interface, this could be -1 as "none", and this leads to OOB access for index[] and other parameters.
Add a sanity check for the card index and warn/correct it if it's a value out of the range.
Affected Software
Event History
Frequently Asked Questions
Who is realistically exposed to this issue?
Systems using the ALSA mpu401 driver are exposed when a device is manually bound through the sysfs interface. Devices created by the driver itself during module probe are described as operating with valid card indices.
What does an attacker or local user need to do to trigger the vulnerable path?
They need to manually bind an mpu401 device through sysfs with an invalid device card index, such as -1, which represents "none." The driver previously trusted that value and could access index-related arrays out of bounds.
Is the default driver-created configuration affected?
The description indicates that devices created by the driver at module probe time use proper card index values. The vulnerable condition is associated with manual sysfs binding rather than the driver's normal device creation path.
What mitigation is available if the fix cannot be applied immediately?
Avoid manually binding mpu401 devices through the sysfs interface with invalid or unset card indices. In particular, do not use -1 or other values outside the valid card index range.