CVE-2026-31576

About vulnerability

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

media: hackrf: fix to not free memory after the device is registered in hackrf_probe()

In hackrf driver, the following race condition occurs:

CPU0						CPU1
hackrf_probe()
kzalloc(); // alloc hackrf_dev
....
v4l2_device_register();
....
fd = sys_open("/path/to/dev"); // open hackrf fd
....
v4l2_device_unregister();
....
kfree(); // free hackrf_dev
....
sys_ioctl(fd, ...);
v4l2_ioctl();
video_is_registered() // UAF!!
....
sys_close(fd);
v4l2_release() // UAF!!
hackrf_video_release()
kfree(); // DFB!!

When a V4L2 or video device is unregistered, the device node is removed so new open() calls are blocked.

However, file descriptors that are already open-and any in-flight I/O-do not terminate immediately; they remain valid until the last reference is dropped and the driver’s release() is invoked.

Therefore, freeing device memory on the error path after hackrf_probe() has registered dev it will lead to a race to use-after-free vuln, since those already-open handles haven’t been released yet.

And since release() free memory too, race to use-after-free and double-free vuln occur.

To prevent this, if device is registered from probe(), it should be modified to free memory only through release() rather than calling kfree() directly.

Affected product:

AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Debian 10 ELS , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

kernel @ 3.10.0 (+18 more)

Live-patch status from KernelCare for each operating system.