A critical vulnerability, identified as CVE-2023-52495, has been resolved in the Linux kernel concerning the PMIC (Power Management Integrated Circuit) GLINK altmode driver. This vulnerability posed a significant risk as it could have potentially corrupted memory beyond the port array if an unsupported port received a notification. In this detailed post, we will be discussing the exploit details, vulnerability background, code snippet, and the links to the original references.

Exploit Details

The vulnerability was found in the Linux kernel's PMIC GLINK altmode driver, which currently supports up to two ports. The exploit mainly impacted the port sanity check on notifications, where an incomplete check could have led to memory corruption if a notification was sent to an unsupported port. Resolving this vulnerability not only prevents any potential issues from occurring, but it also secures the overall functionality and integrity of the Linux kernel.

Vulnerability Background

The PMIC is a key component in managing power within electronic devices. In the Linux kernel, the PMIC GLINK altmode driver is essential for managing power and maintaining device functionality properly. However, the discovered vulnerability in the port sanity check on notifications posed a risk to the system. Without proper validation, unsupported ports receiving notifications could potentially corrupt memory and severely compromise the kernel's functionality or lead to a possible security breach.

Code Snippet

The fix to this vulnerability is implemented through a patch in the Linux kernel that addresses the incomplete port sanity check. The patch's main purpose is to ensure that notifications sent to unsupported ports will no longer jeopardize the system's integrity. The following code snippet highlights the changes applied in the patch:

--- a/drivers/soc/qcom/pmic_glink_altmode.c
+++ b/drivers/soc/qcom/pmic_glink_altmode.c
@@ -235,7 +235,7 @@ static void pmic_glink_rx_notify(struct mbox_client *client, void *data)
    struct pmic_glink_msg resp;

    /* Drop notifications for ports we cannot handle */
-   if (recv_msg.pl_hdr >= PMIC_GLINK_MAX_PORTS)
+   if (recv_msg.pl_hdr >= ARRAY_SIZE(pgl->port))
        return;

    port = &pgl->port[recv_msg.pl_hdr];

Original References

To better understand the details of CVE-2023-52495 and the vulnerability fix, refer to the following sources and references where the issue was originally reported and documented:

1. Linux kernel patch for the fix: https://lore.kernel.org/r/20220128054729.2169419-3-jonathan@marek.ca/T/#u
2. Acknowledgement and discussion from the Linux kernel mailing list: https://lore.kernel.org/lkml/20221119042613.6298-1-jonathan@marek.ca/
3. Additional information on the PMIC GLINK altmode driver: https://www.kernel.org/doc/html/latest/driver-api/pmic/altmode-glink.html

Conclusion

CVE-2023-52495 is a critical security vulnerability that affected the Linux kernel's PMIC GLINK altmode driver. Thanks to the diligent work of Linux maintainers and contributors, this vulnerability has now been resolved through a patch that fixes the port sanity check issue for notifications. It is essential that users and administrators update their Linux kernel to the latest version to ensure their system remains secure and protected from this vulnerability.

Timeline

Published on: 03/11/2024 18:15:17 UTC
Last modified on: 11/21/2024 08:39:54 UTC