CVE-2023-52884 in Linux
Summary
by MITRE • 06/21/2024
In the Linux kernel, the following vulnerability has been resolved:
Input: cyapa - add missing input core locking to suspend/resume functions
Grab input->mutex during suspend/resume functions like it is done in other input drivers. This fixes the following warning during system suspend/resume cycle on Samsung Exynos5250-based Snow Chromebook:
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WARNING: CPU: 1 PID: 1680 at drivers/input/input.c:2291 input_device_enabled+0x68/0x6c Modules linked in: ... CPU: 1 PID: 1680 Comm: kworker/u4:12 Tainted: G W 6.6.0-rc5-next-20231009 #14109 Hardware name: Samsung Exynos (Flattened Device Tree) Workqueue: events_unbound async_run_entry_fn unwind_backtrace from show_stack+0x10/0x14 show_stack from dump_stack_lvl+0x58/0x70 dump_stack_lvl from __warn+0x1a8/0x1cc __warn from warn_slowpath_fmt+0x18c/0x1b4 warn_slowpath_fmt from input_device_enabled+0x68/0x6c input_device_enabled from cyapa_gen3_set_power_mode+0x13c/0x1dc cyapa_gen3_set_power_mode from cyapa_reinitialize+0x10c/0x15c cyapa_reinitialize from cyapa_resume+0x48/0x98 cyapa_resume from dpm_run_callback+0x90/0x298 dpm_run_callback from device_resume+0xb4/0x258 device_resume from async_resume+0x20/0x64 async_resume from async_run_entry_fn+0x40/0x15c async_run_entry_fn from process_scheduled_works+0xbc/0x6a8 process_scheduled_works from worker_thread+0x188/0x454 worker_thread from kthread+0x108/0x140 kthread from ret_from_fork+0x14/0x28 Exception stack(0xf1625fb0 to 0xf1625ff8) ... ---[ end trace 0000000000000000 ]---
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WARNING: CPU: 1 PID: 1680 at drivers/input/input.c:2291 input_device_enabled+0x68/0x6c Modules linked in: ... CPU: 1 PID: 1680 Comm: kworker/u4:12 Tainted: G W 6.6.0-rc5-next-20231009 #14109 Hardware name: Samsung Exynos (Flattened Device Tree) Workqueue: events_unbound async_run_entry_fn unwind_backtrace from show_stack+0x10/0x14 show_stack from dump_stack_lvl+0x58/0x70 dump_stack_lvl from __warn+0x1a8/0x1cc __warn from warn_slowpath_fmt+0x18c/0x1b4 warn_slowpath_fmt from input_device_enabled+0x68/0x6c input_device_enabled from cyapa_gen3_set_power_mode+0x13c/0x1dc cyapa_gen3_set_power_mode from cyapa_reinitialize+0x10c/0x15c cyapa_reinitialize from cyapa_resume+0x48/0x98 cyapa_resume from dpm_run_callback+0x90/0x298 dpm_run_callback from device_resume+0xb4/0x258 device_resume from async_resume+0x20/0x64 async_resume from async_run_entry_fn+0x40/0x15c async_run_entry_fn from process_scheduled_works+0xbc/0x6a8 process_scheduled_works from worker_thread+0x188/0x454 worker_thread from kthread+0x108/0x140 kthread from ret_from_fork+0x14/0x28 Exception stack(0xf1625fb0 to 0xf1625ff8) ... ---[ end trace 0000000000000000 ]---
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Analysis
by VulDB Data Team • 11/07/2024
The vulnerability identified as CVE-2023-52884 resides within the Linux kernel's input subsystem, specifically affecting the cyapa driver used for touchpad devices on certain hardware platforms. This issue manifests as a race condition during system suspend and resume operations, where the driver fails to properly acquire the input core mutex before accessing input device state information. The problem is particularly evident on Samsung Exynos5250-based Snow Chromebook devices, where the kernel generates repeated warning messages indicating potential data corruption or inconsistent device states during power management transitions. The warning originates from the input_device_enabled function located at drivers/input/input.c line 2291, suggesting that concurrent access to input device structures occurs without proper synchronization mechanisms.
The technical flaw stems from the cyapa driver's implementation of suspend and resume functions, which do not follow the standard pattern used by other input drivers in the kernel. While most input drivers correctly acquire the input->mutex before performing operations on input devices during power management events, the cyapa driver omits this crucial step. This omission creates a scenario where multiple threads or processes can simultaneously access and modify the same input device data structures, leading to potential memory corruption, inconsistent device states, and system instability. The call stack shows the sequence of function calls leading to the warning, starting from cyapa_resume through cyapa_reinitialize to cyapa_gen3_set_power_mode, ultimately reaching input_device_enabled where the mutex protection should have been applied. This pattern aligns with CWE-362, which describes a race condition vulnerability where concurrent access to shared resources occurs without proper synchronization.
The operational impact of this vulnerability extends beyond simple warning messages, as it can lead to complete system instability or device malfunction during suspend/resume cycles. When a system transitions between power states, the input subsystem must maintain consistent device state information to ensure proper functionality upon wake. Without proper locking, the cyapa driver may attempt to access or modify device properties while another process is simultaneously altering the same data, potentially causing kernel panics or device driver failures. The warning messages indicate that the kernel has detected an unsafe access pattern, which could result in data loss or corrupted device state information that persists across power transitions. This vulnerability particularly affects embedded systems and mobile devices where power management is critical, as improper handling of suspend/resume operations can lead to complete system lockups or unresponsive input devices.
Mitigation for this vulnerability requires implementing proper mutex locking mechanisms within the cyapa driver's suspend and resume functions, aligning them with the patterns used by other input drivers in the kernel. The fix involves adding input->mutex acquisition before any input device state modifications during power management operations, ensuring that all access to device structures is properly synchronized. This approach addresses the root cause by preventing concurrent access to shared input device resources during critical power state transitions. System administrators and device manufacturers should ensure that affected systems are updated with kernel versions containing the patch, which implements the missing locking mechanism. The solution adheres to established kernel development practices and follows the ATT&CK framework's concept of privilege escalation through system-level vulnerabilities, as proper synchronization prevents unauthorized or unintended modifications to kernel data structures. Organizations should also implement comprehensive testing of power management features on affected hardware to verify that the fix resolves the race condition without introducing new issues.