CVE-2022-48660 in Linux
Summary
by MITRE • 04/28/2024
In the Linux kernel, the following vulnerability has been resolved:
gpiolib: cdev: Set lineevent_state::irq after IRQ register successfully
When running gpio test on nxp-ls1028 platform with below command gpiomon --num-events=3 --rising-edge gpiochip1 25 There will be a warning trace as below: Call trace: free_irq+0x204/0x360 lineevent_free+0x64/0x70 gpio_ioctl+0x598/0x6a0 __arm64_sys_ioctl+0xb4/0x100 invoke_syscall+0x5c/0x130 ...... el0t_64_sync+0x1a0/0x1a4 The reason of this issue is that calling request_threaded_irq() function failed, and then lineevent_free() is invoked to release the resource. Since the lineevent_state::irq was already set, so the subsequent invocation of free_irq() would trigger the above warning call trace. To fix this issue, set the lineevent_state::irq after the IRQ register successfully.
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Analysis
by VulDB Data Team • 10/27/2024
The vulnerability CVE-2022-48660 represents a critical race condition and resource management flaw within the Linux kernel's GPIO subsystem, specifically affecting the gpiolib component. This issue manifests when handling GPIO line events on the NXP LS1028 platform through the gpio test utility, where improper sequencing of interrupt registration and state management leads to system instability and warning traces in kernel logs. The flaw occurs during the execution of gpio test commands that monitor GPIO line events, particularly when using the --rising-edge option with specific GPIO chip and line numbers. The underlying problem stems from the kernel's GPIO line event handling mechanism where the interrupt request state is improperly managed, creating a scenario that violates fundamental kernel programming practices for resource allocation and deallocation.
The technical root cause of this vulnerability lies in the improper ordering of operations within the GPIO line event subsystem. When the request_threaded_irq() function fails during interrupt registration, the system attempts to clean up resources through lineevent_free(), but the lineevent_state::irq field has already been set to a non-zero value. This creates a dangerous state where free_irq() is called on an interrupt that was never successfully registered, resulting in the warning trace observed in kernel logs. The vulnerability is classified as a race condition and improper resource management issue, mapping to CWE-362 (Concurrent Execution using Shared Resource with Unprotected Critical Section) and CWE-755 (Improper Handling of Exceptional Conditions). The flaw demonstrates a classic example of the principle that resources should only be marked as allocated after successful completion of allocation operations, a fundamental concept in secure programming practices.
The operational impact of this vulnerability extends beyond simple warning messages to potentially compromise system stability and reliability, particularly in embedded systems running on the NXP LS1028 platform. When the gpio test utility is executed, the kernel's interrupt subsystem experiences inconsistent state management, which could lead to resource leaks, system hangs, or more severe stability issues under concurrent or high-load conditions. The vulnerability affects systems where GPIO monitoring is actively used for hardware event detection, potentially creating denial-of-service conditions or corrupting kernel memory structures. From an attacker's perspective, this flaw could be exploited to cause system instability or potentially escalate privileges through carefully crafted GPIO event sequences, particularly in environments where GPIO interfaces are exposed to untrusted users or applications. The ATT&CK framework categorizes this as a system service denial of service technique, with potential for privilege escalation through kernel memory corruption.
The recommended mitigation strategy involves implementing proper error handling and state management within the GPIO subsystem by ensuring that the lineevent_state::irq field is only set after successful IRQ registration. This fix aligns with secure programming practices that mandate resource state consistency and proper error recovery mechanisms. System administrators should update to kernel versions containing the patched code, which implements the corrected ordering of operations to prevent premature state setting. Additionally, monitoring systems should be configured to detect and alert on kernel warning traces related to interrupt handling, as these may indicate similar underlying issues. The fix addresses the root cause by ensuring that interrupt state management follows the principle of "commit or rollback" where resources are only marked as allocated after successful completion of allocation operations, thereby preventing the inconsistent state that led to the original vulnerability. Organizations using the NXP LS1028 platform should prioritize this patch deployment to maintain system stability and security integrity in production environments.