CVE-2023-53124 in Linux
Summary
by MITRE • 05/02/2025
In the Linux kernel, the following vulnerability has been resolved:
scsi: mpt3sas: Fix NULL pointer access in mpt3sas_transport_port_add()
Port is allocated by sas_port_alloc_num() and rphy is allocated by either sas_end_device_alloc() or sas_expander_alloc(), all of which may return NULL. So we need to check the rphy to avoid possible NULL pointer access.
If sas_rphy_add() returned with failure, rphy is set to NULL. We would access the rphy in the following lines which would also result NULL pointer access.
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Analysis
by VulDB Data Team • 11/10/2025
The vulnerability identified as CVE-2023-53124 represents a critical NULL pointer dereference flaw within the Linux kernel's SCSI multipath target 3 SAS (mpt3sas) driver component. This issue resides in the mpt3sas_transport_port_add() function where improper error handling leads to potential system crashes and denial of service conditions. The vulnerability manifests when the driver attempts to process SCSI transport port additions without adequately validating the return values from underlying allocation functions, creating a scenario where null pointers are dereferenced during normal operation.
The technical root cause stems from the improper handling of return values from multiple allocation functions within the SCSI transport subsystem. Specifically, the sas_port_alloc_num() function allocates port resources while sas_end_device_alloc() and sas_expander_alloc() handle endpoint and expander allocations respectively. When any of these allocation functions fail or return NULL pointers, the subsequent code path does not properly validate these null returns before attempting to access the rphy (SCSI remote PHY) structure. The vulnerability occurs because the driver does not check whether rphy is NULL after calling sas_rphy_add() which can result in setting rphy to NULL upon failure, yet the code continues to dereference this null pointer in subsequent operations.
This flaw directly maps to CWE-476, which identifies NULL pointer dereference as a common software vulnerability pattern where programs attempt to access memory through null pointers. The operational impact of CVE-2023-53124 extends beyond simple system instability as it affects the core storage subsystem of Linux systems, potentially leading to complete system crashes, data loss, and denial of service conditions for storage operations. The vulnerability is particularly concerning in enterprise environments where reliable storage connectivity is critical, as it can cause unexpected system reboots during normal storage operations, disrupting critical business processes and potentially leading to data corruption scenarios.
From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.001 which covers network denial of service attacks, and T1562.001 which involves disabling security tools. An attacker could potentially exploit this vulnerability to cause system instability by triggering the specific code path that leads to NULL pointer dereference, resulting in system crashes and service disruption. The attack surface is primarily limited to systems running the affected Linux kernel version with mpt3sas drivers enabled, particularly those utilizing SAS storage configurations. The vulnerability is classified as a privilege escalation risk since it can be triggered by normal system operations without requiring special privileges, making it particularly dangerous in multi-user environments where unprivileged users might inadvertently trigger the flaw.
Mitigation strategies should focus on immediate kernel updates to versions containing the patched code that properly validates return values from allocation functions before dereferencing pointers. System administrators should prioritize patching affected systems, particularly those in production environments where storage reliability is paramount. Additionally, monitoring systems should be configured to detect unusual system crashes or reboots that might indicate exploitation attempts. The fix implemented in the patch involves adding proper null pointer checks after allocation calls to ensure that rphy is validated before any operations are performed on it, preventing the NULL pointer dereference that previously occurred. Organizations should also consider implementing additional runtime protections such as kernel lockdown mechanisms and enhanced logging to detect potential exploitation attempts.