A new vulnerability with the CVE-ID CVE-2022-49924 has been discovered and resolved in the Linux kernel. The vulnerability is related to the Near Field Communication (NFC) module and specifically targets the fdp_nci_send() function. This vulnerability can lead to potential memory leaks, which can pose security risks by causing the system to crash or allowing attackers to exploit the leaked memory data. In response to this vulnerability, a patch has been implemented to fix the memory leak issue by ensuring the proper freeing of memory resources.

Original References

To better understand the vulnerability and the implemented fix, it is recommended to consult the following resources:
1. Linux kernel source code repository
2. CVE-2022-49924 record in the National Vulnerability Database

Vulnerability Details

The memory leak vulnerability in the Linux kernel exists because of the improper handling of memory resources, specifically in the fdp_nci_send() function that manages communication in the NFC module. Normally, a socket buffer (skb) is used to manage the communication data, but the memory occupied by the skb is not freed when the fdp_nci_i2c_write() function completes execution. This leads to leaked memory that accumulates over time, causing the system to use up more and more memory, eventually leading to a system crash or other potential vulnerabilities.

Here's a snippet of the problematic code in the fdp_nci_send() function

static int fdp_nci_send(struct sk_buff *skb, struct nci_dev *ndev)
{
  ...
  ret = fdp_nci_i2c_write(dev, skb->data, skb->len);
  ...

  return ret;
}

As shown in the snippet above, the fdp_nci_send() function calls fdp_nci_i2c_write() to manage the data communication. However, the skb memory is not freed after the i2c_write() function is completed, leading to a memory leak.

Exploit Solution

The fix for this vulnerability is relatively simple but crucial. The key is to ensure that the memory taken up by the skb is released after the fdp_nci_i2c_write() function finishes its work. To ensure this, a patch modifies the fdp_nci_send() function to include a call to consume_skb() after the fdp_nci_i2c_write() function, as shown in the code snippet below:

static int fdp_nci_send(struct sk_buff *skb, struct nci_dev *ndev)
{
  ...
  ret = fdp_nci_i2c_write(dev, skb->data, skb->len);

  /* Free the skb memory after the write function completes */
  consume_skb(skb);

  return ret;
}

With the additional call to consume_skb(), the memory occupied by the skb is now properly released, effectively fixing the memory leak vulnerability associated with CVE-2022-49924.

Conclusion

CVE-2022-49924 highlights the importance of properly managing memory resources and ensuring that functions are correctly implemented to prevent potential memory leaks. Thanks to the timely detection and patching of this vulnerability, Linux systems running the affected kernel can now avoid the associated security risks. Users and system administrators should ensure that their systems are updated with the latest patches to maintain a secure and stable environment.

Timeline

Published on: 05/01/2025 15:16:18 UTC
Last modified on: 05/07/2025 13:28:24 UTC