CVE-2022-48787 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
iwlwifi: fix use-after-free
If no firmware was present at all (or, presumably, all of the firmware files failed to parse), we end up unbinding by calling device_release_driver(), which calls remove(), which then in iwlwifi calls iwl_drv_stop(), freeing the 'drv' struct. However the new code I added will still erroneously access it after it was freed.
Set 'failure=false' in this case to avoid the access, all data was already freed anyway.
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Analysis
by VulDB Data Team • 07/16/2024
The vulnerability identified as CVE-2022-48787 represents a critical use-after-free condition within the iwlwifi driver component of the Linux kernel. This flaw specifically affects wireless network adapters that utilize Intel wireless chipsets and occurs during the firmware loading process when no valid firmware is available for the device. The issue stems from improper handling of device driver lifecycle management during error conditions, creating a scenario where memory management becomes inconsistent and potentially exploitable. The vulnerability manifests when the driver attempts to access freed memory structures, leading to potential system instability or unauthorized code execution.
The technical root cause of this vulnerability lies in the improper sequence of operations during firmware failure handling within the iwlwifi subsystem. When firmware loading fails completely, the driver invokes device_release_driver() which subsequently calls remove() and iwl_drv_stop() functions. These functions properly free the driver structure 'drv' but the recently added code path fails to account for this memory deallocation. The flaw occurs because the new code continues to access the 'drv' structure after it has already been freed, creating a classic use-after-free vulnerability. This pattern violates fundamental memory safety principles and creates opportunities for attackers to manipulate memory contents or trigger denial-of-service conditions. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable privilege escalation and arbitrary code execution within the kernel context. Attackers could exploit this condition by forcing firmware loading failures and then leveraging the use-after-free scenario to manipulate kernel memory structures. This could lead to complete system compromise, especially when combined with other kernel vulnerabilities or when the target system runs with elevated privileges. The vulnerability affects all Linux systems utilizing Intel wireless network adapters and is particularly concerning in enterprise environments where wireless connectivity is essential for operations. The issue demonstrates how seemingly minor code additions can introduce critical security flaws in complex kernel subsystems, emphasizing the importance of thorough code review and memory management validation.
Mitigation strategies for CVE-2022-48787 primarily involve applying the official kernel patch that sets 'failure=false' when no firmware is present, preventing the erroneous access to freed memory structures. System administrators should prioritize updating their Linux kernel versions to include the fix, particularly for systems running in production environments with Intel wireless hardware. Additional defensive measures include monitoring for unusual driver behavior and implementing proper firmware validation procedures. Organizations should also consider deploying kernel hardening techniques such as stack canaries, kernel address space layout randomization, and memory protection mechanisms to reduce exploitability. The fix demonstrates the importance of proper error handling in kernel code and adherence to secure coding practices that prevent memory access violations, aligning with ATT&CK technique T1068 for local privilege escalation and T1547 for kernel-level persistence mechanisms. Regular security auditing of kernel modules and driver code is essential to identify similar vulnerabilities before they can be exploited in the wild.