CVE-2023-52498 in Linux
Summary
by MITRE • 03/11/2024
In the Linux kernel, the following vulnerability has been resolved:
PM: sleep: Fix possible deadlocks in core system-wide PM code
It is reported that in low-memory situations the system-wide resume core code deadlocks, because async_schedule_dev() executes its argument function synchronously if it cannot allocate memory (and not only in that case) and that function attempts to acquire a mutex that is already held. Executing the argument function synchronously from within dpm_async_fn() may also be problematic for ordering reasons (it may cause a consumer device's resume callback to be invoked before a requisite supplier device's one, for example).
Address this by changing the code in question to use async_schedule_dev_nocall() for scheduling the asynchronous execution of device suspend and resume functions and to directly run them synchronously if async_schedule_dev_nocall() returns false.
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Analysis
by VulDB Data Team • 12/13/2024
The vulnerability described in CVE-2023-52498 represents a critical deadlock condition within the Linux kernel's power management subsystem, specifically affecting the system-wide suspend and resume functionality. This issue manifests when the kernel operates under low-memory conditions, where the core power management code becomes unresponsive due to improper handling of asynchronous execution contexts. The problem stems from the behavior of the async_schedule_dev() function which, under memory pressure, falls back to synchronous execution instead of maintaining its asynchronous nature. This design flaw creates a fundamental race condition where the function attempts to acquire a mutex that is already held by the calling thread, resulting in a circular dependency that halts system operations.
The technical root cause of this vulnerability lies in the improper memory allocation handling within the power management framework's asynchronous scheduling mechanism. When memory allocation fails during the execution of async_schedule_dev(), the function defaults to synchronous execution rather than gracefully handling the failure condition. This behavior violates the fundamental principle of asynchronous programming where failure conditions should be handled without blocking execution paths. The issue specifically affects the dpm_async_fn() function which serves as the core execution context for device power management operations, and the synchronous execution within this context creates ordering dependencies that can cause device resume callbacks to execute in incorrect sequences. According to CWE-362, this represents a race condition vulnerability where concurrent execution paths interfere with each other due to improper synchronization mechanisms.
The operational impact of this vulnerability extends beyond simple system hangs, potentially leading to complete system lockups during power management transitions, particularly during system-wide resume operations. When the kernel encounters low-memory conditions, the deadlock scenario becomes increasingly likely as the system's ability to allocate memory for asynchronous operations diminishes. This creates a cascading failure effect where the very mechanism designed to handle system power states becomes the source of system instability. The vulnerability affects the reliability of power management features across all Linux kernel versions that include the affected code paths, potentially impacting servers, embedded systems, and desktop environments where memory constraints may occur during normal operations. Attackers could potentially exploit this by forcing memory pressure conditions to trigger the deadlock scenario, though the primary concern is the system's inherent instability rather than direct exploitation.
The mitigation strategy implemented in the fix addresses the core issue by introducing a more robust asynchronous execution mechanism using async_schedule_dev_nocall() instead of the problematic async_schedule_dev(). This change ensures that when asynchronous scheduling fails due to memory constraints, the system can still proceed with synchronous execution without creating deadlock conditions. The solution properly handles the failure case by directly executing the device suspend and resume functions synchronously when the asynchronous scheduling mechanism cannot allocate necessary resources, thereby maintaining system stability while preserving the intended functionality. This approach aligns with ATT&CK technique T1484.001 which addresses privilege escalation through kernel-level vulnerabilities, as the fix prevents unauthorized system state manipulation through power management subsystem instability. The implementation also follows security best practices by ensuring that system-critical operations maintain their intended execution flow regardless of resource availability conditions. The solution addresses both the immediate deadlock condition and the ordering concerns that could lead to incorrect device power state transitions, thereby restoring the reliability of the Linux kernel's power management subsystem under all operating conditions.