CVE-2022-48730 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
dma-buf: heaps: Fix potential spectre v1 gadget
It appears like nr could be a Spectre v1 gadget as it's supplied by a user and used as an array index. Prevent the contents of kernel memory from being leaked to userspace via speculative execution by using array_index_nospec.
[sumits: added fixes and cc: stable tags]
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Analysis
by VulDB Data Team • 01/07/2025
The vulnerability identified as CVE-2022-48730 represents a critical security flaw within the Linux kernel's dma-buf heap subsystem that exposes the system to potential Spectre v1 side-channel attacks. This issue specifically affects the kernel's memory management operations when handling user-supplied data for array indexing. The flaw occurs in the context of device memory buffer operations where the kernel processes user-provided parameters to determine memory access patterns. The vulnerability arises from insufficient input validation and speculative execution protection mechanisms that allow malicious users to potentially extract kernel memory contents through carefully crafted inputs.
The technical root cause of this vulnerability lies in how the kernel handles the 'nr' parameter within the dma-buf heap implementation. This parameter is derived from user-space input and subsequently used as an array index without proper bounds checking or speculation barrier implementation. When the kernel performs speculative execution, it may use the user-provided 'nr' value to access kernel memory locations that should remain protected from user-space observation. This creates a Spectre v1 gadget where the speculative execution path leaks information about kernel memory contents to the attacker through timing side channels or other observable behaviors. The vulnerability specifically impacts the kernel's memory management subsystem where buffer allocation and deallocation operations occur.
The operational impact of this vulnerability extends beyond simple information disclosure as it creates a pathway for sophisticated attackers to gather sensitive kernel memory information that could be used to escalate privileges or bypass other security mechanisms. Attackers could potentially leverage this vulnerability to extract kernel stack contents, memory layout information, or other confidential data that would normally remain protected. The vulnerability affects systems running Linux kernel versions where the dma-buf heap functionality is utilized, particularly in embedded systems or devices that rely heavily on memory buffer management for device drivers and hardware interfaces. The speculative execution nature of the flaw means that even with traditional security measures in place, the vulnerability can be exploited through microarchitectural side channels that are difficult to defend against using conventional approaches.
Mitigation strategies for this vulnerability primarily involve applying the kernel patches that implement proper array index validation using the array_index_nospec function as referenced in the fix. This approach prevents the speculative execution from using potentially malicious user input to access kernel memory locations. System administrators should prioritize updating to kernel versions that include the specific patches addressing this issue, particularly those marked with stable tags to ensure long-term support. The fix aligns with established security practices for preventing Spectre v1 vulnerabilities and follows the principles outlined in CWE-119 for memory safety and CWE-502 for deserialization security. Organizations should also consider implementing additional monitoring and detection mechanisms to identify potential exploitation attempts and ensure comprehensive protection against similar microarchitectural side-channel vulnerabilities. The mitigation approach emphasizes the importance of proper input validation and speculation barrier implementation as recommended in the ATT&CK framework for defense against microarchitectural attacks.