CVE-2025-38634 in Linux
Summary
by MITRE • 08/22/2025
In the Linux kernel, the following vulnerability has been resolved:
power: supply: cpcap-charger: Fix null check for power_supply_get_by_name
In the cpcap_usb_detect() function, the power_supply_get_by_name() function may return `NULL` instead of an error pointer. To prevent potential null pointer dereferences, Added a null check.
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Analysis
by VulDB Data Team • 05/28/2026
The vulnerability identified as CVE-2025-38634 represents a critical null pointer dereference issue within the Linux kernel's power supply subsystem, specifically affecting the cpcap-charger driver. This flaw exists in the cpcap_usb_detect() function where the power_supply_get_by_name() API call does not consistently return error pointers when encountering failures, instead potentially returning NULL values that can lead to system crashes or unexpected behavior. The issue stems from improper handling of the power supply enumeration mechanism that is fundamental to USB charging detection in certain hardware platforms. The vulnerability affects systems utilizing the cpcap charger driver, which is commonly found in mobile devices and embedded systems that rely on the Freescale cpcap power management controller for battery charging operations.
The technical implementation of this vulnerability occurs when the cpcap_usb_detect() function attempts to retrieve a power supply object using power_supply_get_by_name() without proper validation of the returned pointer. When the function fails to locate or access the specified power supply, it may return NULL instead of an appropriate error indicator, leading to subsequent dereference operations that cause system instability. This null pointer dereference creates a condition where the kernel can attempt to access memory locations that have not been properly allocated, potentially resulting in kernel oops, system crashes, or in worst-case scenarios, privilege escalation opportunities. The flaw specifically manifests during USB charging detection routines where the system attempts to verify charging status through the power supply framework, making it particularly dangerous in mobile environments where charging operations are frequent and critical to user experience.
The operational impact of CVE-2025-38634 extends beyond simple system crashes to potentially compromise the overall stability and security posture of affected Linux systems. When triggered, the vulnerability can cause unexpected device shutdowns or reboots during charging operations, leading to data loss and user inconvenience. In embedded systems and mobile devices, this could result in complete system failure during critical charging scenarios, particularly affecting devices that rely on the cpcap power management controller for battery charging control. The vulnerability also presents potential attack surface implications, as an attacker could potentially exploit this condition to cause denial of service attacks or in combination with other vulnerabilities, potentially escalate privileges. This aligns with CWE-476, which specifically addresses NULL pointer dereference conditions, and represents a classic example of improper error handling in kernel space operations.
Mitigation strategies for CVE-2025-38634 focus on implementing proper null pointer validation within the cpcap-charger driver code. The solution involves adding explicit null checks after calls to power_supply_get_by_name() to ensure that the returned pointer is valid before attempting any dereference operations. This approach aligns with best practices for kernel development and security hardening as recommended in the Linux kernel security documentation and follows ATT&CK technique T1499.004 for system disruption. System administrators should ensure that affected systems are updated with the patched kernel version that includes the null check implementation. Additionally, monitoring for unusual charging behavior or system instability during USB connection events can help identify potential exploitation attempts. The fix demonstrates proper defensive programming practices and reinforces the importance of validating all kernel API return values, particularly in power management subsystems where reliability is paramount for user safety and system stability. Organizations should prioritize patching this vulnerability across all affected Linux-based systems, particularly those in mobile and embedded environments where charging operations are frequent and critical to overall device functionality.