CVE-2023-52877 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
usb: typec: tcpm: Fix NULL pointer dereference in tcpm_pd_svdm()
It is possible that typec_register_partner() returns ERR_PTR on failure. When port->partner is an error, a NULL pointer dereference may occur as shown below.
[91222.095236][ T319] typec port0: failed to register partner (-17)
... [91225.061491][ T319] Unable to handle kernel NULL pointer dereference
at virtual address 000000000000039f [91225.274642][ T319] pc : tcpm_pd_data_request+0x310/0x13fc
[91225.274646][ T319] lr : tcpm_pd_data_request+0x298/0x13fc
[91225.308067][ T319] Call trace:
[91225.308070][ T319] tcpm_pd_data_request+0x310/0x13fc
[91225.308073][ T319] tcpm_pd_rx_handler+0x100/0x9e8
[91225.355900][ T319] kthread_worker_fn+0x178/0x58c
[91225.355902][ T319] kthread+0x150/0x200
[91225.355905][ T319] ret_from_fork+0x10/0x30
Add a check for port->partner to avoid dereferencing a NULL pointer.
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Analysis
by VulDB Data Team • 01/07/2025
The vulnerability CVE-2023-52877 represents a critical null pointer dereference issue within the Linux kernel's USB Type-C subsystem, specifically in the Thunderbolt Controller Protocol Manager tcpm component. This flaw exists in the tcpm_pd_svdm() function where the code fails to properly validate the return value from typec_register_partner() before proceeding with operations that assume a valid partner structure exists. The vulnerability stems from the kernel's USB Type-C typec_register_partner() function which can return an ERR_PTR on failure conditions, yet the tcpm_pd_svdm() implementation does not adequately check for this error condition before attempting to access the partner structure members. When port->partner contains an error pointer rather than a valid structure reference, subsequent operations attempt to dereference this invalid pointer, leading to kernel oops and potential system instability.
The technical exploitation of this vulnerability occurs during USB Type-C communication processing when the kernel receives and processes PD (Power Delivery) messages through the TCPM subsystem. The call trace demonstrates that the error originates from tcpm_pd_data_request() function which is invoked through tcpm_pd_rx_handler() in response to received PD messages. When the typec_register_partner() function fails to register a partner device, it returns an error pointer that is stored in port->partner. However, the tcpm_pd_svdm() function does not validate this condition before accessing partner structure fields, resulting in a null pointer dereference at virtual address 0x39f. This specific memory access pattern aligns with CWE-476 Null Pointer Dereference, which is classified as a common weakness in software development where programs attempt to access memory through a pointer that has not been properly validated as non-null.
The operational impact of this vulnerability extends beyond simple system crashes, as it represents a potential denial of service condition that can affect any Linux system running with USB Type-C support. The vulnerability affects systems where USB Type-C ports are actively used for power delivery negotiations or device connections, particularly in laptops, desktops, and embedded systems that rely on Type-C for charging and data transfer operations. The kernel panic resulting from this null pointer dereference can cause complete system instability, requiring manual reboot to restore normal operation. This vulnerability is particularly concerning in server environments or embedded systems where unexpected system crashes can lead to service interruptions or data loss. The flaw can be triggered by malicious or faulty USB Type-C devices that cause the partner registration process to fail, potentially enabling an attacker to cause system crashes or potentially escalate privileges through carefully crafted USB Type-C communications.
Mitigation strategies for CVE-2023-52877 should focus on implementing proper error checking and validation within the tcpm_pd_svdm() function to ensure that port->partner is validated before any dereference operations occur. The fix requires adding explicit checks to verify that port->partner is not an error pointer before accessing partner structure members, which aligns with ATT&CK technique T1068 for privilege escalation through kernel vulnerabilities. System administrators should ensure that all Linux kernel updates are applied promptly, particularly those containing the specific patch for this tcpm subsystem vulnerability. Additional defensive measures include monitoring for unusual Type-C port activity and implementing proper kernel module access controls to limit potential exploitation vectors. The vulnerability demonstrates the importance of proper error handling in kernel space code and highlights the need for comprehensive testing of error conditions in USB subsystem implementations, particularly in critical components like the TCPM that handle power delivery negotiations and device communication protocols.