CVE-2022-45887: Memory Leak Vulnerability in the Linux Kernel Affecting DVB Frontend Detach Calls in Drivers

A recently discovered security vulnerability, identified as CVE-2022-45887, affects the Linux kernel up to version 6..9. The issue is caused by a memory leak in the drivers/media/usb/ttusb-dec/ttusb_dec.c file, which can potentially be exploited by malicious individuals or software. This vulnerability stems from the lack of a dvb_frontend_detach call, leading to improper handling of memory resources.

In this post, we will dive deeper into the nature of this memory leak, its potential impact, and technical details, including code snippets and original references for further investigation.

Technical Details

The vulnerability is present in the Linux kernel's handling of Digital Video Broadcasting (DVB) frontend devices. Specifically, the issue affects the ttusb_dec driver, which is located in the drivers/media/usb/ttusb-dec/ttusb_dec.c file.

The memory leak occurs due to the lack of a dvb_frontend_detach call, which is responsible for releasing the resources associated with a DVB frontend when the device is no longer needed. The code snippet below shows the function where the memory leak occurs:

static int ttusb_dec_probe(struct usb_interface *intf,
			   const struct usb_device_id *id)
{
	struct ttusb_dec *dec;
	int result;

	dec = kzalloc(sizeof(struct ttusb_dec), GFP_KERNEL);
	if (dec == NULL)
		return -ENOMEM;

	/* Initialization of 'dec' structure... */

	result = dvb_register_frontend(&dec->adapter, &dec->frontend);

	return result;
}

As seen in the code snippet, the ttusb_dec_probe function allocates memory for the ttusb_dec structure but does not include a call to dvb_frontend_detach to free the memory when the device is no longer needed. This omission eventually leads to a memory leak, as the Linux kernel is not aware that these resources need to be freed.

Exploit Details

Although this vulnerability does not directly lead to remote code execution or privilege escalation, it can potentially be exploited in Denial-of-Service (DoS) attacks. The memory leak caused by the lack of a dvb_frontend_detach call can ultimately exhaust available memory resources on the affected system, causing it to hang or crash.

An attacker could continuously create and release DVB frontend devices, causing the memory leak to grow and potentially leading to the exhaustion of available memory on the system.

For more information on this vulnerability, you can refer to the following resources

1. The official CVE entry for CVE-2022-45887
2. The Linux kernel source code repository on GitHub
3. DVB API documentation

Conclusion

CVE-2022-45887 is a noteworthy vulnerability affecting the Linux kernel up to version 6..9 due to a memory leak caused by improper handling of DVB frontend device resources. This vulnerability highlights the importance of proper memory management and resource handling in the Linux kernel and any software in general.

To protect your systems against this vulnerability, it is advisable to monitor memory usage on systems using DVB frontend devices and apply any relevant patches as soon as they become available.

Timeline

Published on: 11/25/2022 04:15:00 UTC
Last modified on: 01/20/2023 20:19:00 UTC