CVE-2023-53166 in Linux
Summary
by MITRE • 09/15/2025
In the Linux kernel, the following vulnerability has been resolved:
power: supply: bq25890: Fix external_power_changed race
bq25890_charger_external_power_changed() dereferences bq->charger, which gets sets in bq25890_power_supply_init() like this:
bq->charger = devm_power_supply_register(bq->dev, &bq->desc, &psy_cfg);
As soon as devm_power_supply_register() has called device_add() the external_power_changed callback can get called. So there is a window where bq25890_charger_external_power_changed() may get called while bq->charger has not been set yet leading to a NULL pointer dereference.
This race hits during boot sometimes on a Lenovo Yoga Book 1 yb1-x90f when the cht_wcove_pwrsrc (extcon) power_supply is done with detecting the connected charger-type which happens to exactly hit the small window:
BUG: kernel NULL pointer dereference, address: 0000000000000018 <snip> RIP: 0010:__power_supply_is_supplied_by+0xb/0xb0 <snip> Call Trace: <TASK> __power_supply_get_supplier_property+0x19/0x50 class_for_each_device+0xb1/0xe0 power_supply_get_property_from_supplier+0x2e/0x50 bq25890_charger_external_power_changed+0x38/0x1b0 [bq25890_charger]
__power_supply_changed_work+0x30/0x40 class_for_each_device+0xb1/0xe0 power_supply_changed_work+0x5f/0xe0 <snip>
Fixing this is easy. The external_power_changed callback gets passed the power_supply which will eventually get stored in bq->charger, so bq25890_charger_external_power_changed() can simply directly use the passed in psy argument which is always valid.
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Analysis
by VulDB Data Team • 01/10/2026
The vulnerability described in CVE-2023-53166 represents a critical race condition within the Linux kernel's power supply subsystem, specifically affecting the bq25890 charger driver. This flaw manifests as a NULL pointer dereference that can occur during system boot processes, particularly on certain Lenovo Yoga Book devices. The issue stems from improper synchronization between the initialization of power supply components and the invocation of external power change callbacks, creating a temporal window where system components attempt to access uninitialized memory structures.
The technical root cause involves the bq25890_charger_external_power_changed() function which directly dereferences the bq->charger pointer without proper validation. During driver initialization, the bq->charger field gets populated through devm_power_supply_register() function call, but this registration process includes device_add() which can immediately trigger the external_power_changed callback. This creates a race condition where the callback executes before the initialization completes, resulting in a NULL pointer dereference at memory address 0x0000000000000018. The kernel's call trace reveals the execution path leading to __power_supply_is_supplied_by function, which ultimately fails due to accessing uninitialized memory.
This vulnerability directly maps to CWE-362, which describes a race condition in software where multiple threads or processes access shared resources without proper synchronization mechanisms. The flaw also aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' through kernel-level vulnerabilities that can be exploited to gain elevated privileges. The specific attack surface involves the kernel's power management subsystem, which operates with elevated privileges and can be manipulated to cause system instability or potential privilege escalation.
The operational impact of this vulnerability is significant, particularly during system boot processes when power supply detection occurs. The Lenovo Yoga Book 1 yb1-x90f device specifically exhibits this behavior due to its particular power supply detection timing, but similar issues could affect other devices using the same bq25890 charger driver. The vulnerability can result in kernel panics, system crashes, and potential denial of service conditions that could prevent normal system operation. During boot, the timing of extcon power_supply detection can precisely hit the race window, causing the kernel to crash with a NULL pointer dereference error.
The fix for this vulnerability is straightforward and well-defined, addressing the fundamental synchronization issue without requiring complex architectural changes. The solution involves modifying the bq25890_charger_external_power_changed() function to utilize the passed-in power_supply argument (psy) directly rather than relying on the potentially uninitialized bq->charger pointer. This approach ensures that the callback always operates on a valid power supply object, eliminating the race condition entirely. The fix leverages the fact that the external_power_changed callback receives the appropriate power_supply object as a parameter, making the direct usage of this argument both safe and appropriate. This remediation approach follows established kernel development practices for handling race conditions in power management subsystems and maintains backward compatibility while ensuring robust operation across all supported hardware platforms.