CVE-2026-64236 in Linux
Summary
by MITRE • 07/24/2026
In the Linux kernel, the following vulnerability has been resolved:
i2c: davinci: fix division by zero on missing clock-frequency
When the 'clock-frequency' property is missing from the device tree, the driver falls back to DAVINCI_I2C_DEFAULT_BUS_FREQ. However, this macro was defined in kHz (100), whereas the device tree property is expected in Hz.
The probe function divided the fallback value by 1000, causing integer truncation that resulted in dev->bus_freq = 0. This triggered a deterministic division-by-zero kernel panic when calculating clock dividers later in the probe sequence.
Fix this by redefining DAVINCI_I2C_DEFAULT_BUS_FREQ in Hz (100000) to match the expected device tree property unit, allowing the existing division logic to work correctly for both cases.
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Analysis
by VulDB Data Team • 07/24/2026
This vulnerability resides within the Linux kernel's i2c davinci driver where a fundamental mismatch between data units causes a critical system failure. The issue manifests when device tree configuration lacks the clock-frequency property, triggering a fallback mechanism that relies on the DAVINCI_I2C_DEFAULT_BUS_FREQ macro. The root cause stems from inconsistent unit definitions where the macro was originally specified in kilohertz while device tree properties are conventionally expressed in hertz, creating an arithmetic discrepancy that leads to severe operational consequences.
The technical flaw occurs during driver initialization when the probe function attempts to process the fallback value through a division operation that was designed for hertz-based values but receives kilohertz data. This fundamental unit mismatch results in integer truncation that reduces the intended frequency value to zero, creating a deterministic kernel panic scenario. The arithmetic error specifically targets the bus frequency calculation that occurs later in the probe sequence when clock dividers are computed, making the vulnerability both predictable and exploitable through device tree configuration manipulation.
This vulnerability directly maps to CWE-369: Divide By Zero, where the division operation becomes invalid due to the zero result from integer truncation. The operational impact extends beyond simple system crashes as this represents a denial-of-service condition that can be reliably triggered through specific device tree configurations. The deterministic nature of this panic means that any system utilizing the davinci i2c driver with missing clock-frequency properties will experience kernel panics, effectively preventing normal operation of i2c communication channels.
The mitigation strategy involves redefining the DAVINCI_I2C_DEFAULT_BUS_FREQ macro from 100 kHz to 100000 hz, aligning it with the expected device tree property unit. This simple yet critical change ensures that existing division logic operates correctly for both scenarios - when clock-frequency is explicitly provided in the device tree and when the fallback mechanism is invoked. The fix maintains backward compatibility while resolving the arithmetic inconsistency that led to the kernel panic, demonstrating proper adherence to the principle of least surprise in kernel driver development where unit consistency prevents mathematical errors from cascading into system failures.
From an ATT&CK perspective, this vulnerability represents a privilege escalation vector through denial-of-service conditions that can be exploited by attackers with device tree modification capabilities. The predictable nature of the panic makes it suitable for exploitation in embedded systems where device tree configuration may be accessible to unprivileged users or where malicious firmware updates could trigger the condition. The vulnerability's resolution demonstrates proper defensive programming practices and highlights the importance of unit consistency in kernel-level arithmetic operations that directly affect system stability and availability.
The fix addresses a fundamental design flaw in unit handling between kernel driver components and device tree interfaces, ensuring that the i2c subsystem operates correctly under all configuration scenarios. This change prevents potential exploitation through device tree manipulation while maintaining the intended default bus frequency behavior that aligns with industry standards for i2c communication protocols. The resolution exemplifies proper kernel development practices where attention to data type consistency and unit definitions prevents cascading failures that could compromise entire system operations.
This vulnerability represents a classic case of specification mismatch in embedded systems development where seemingly minor inconsistencies in data representation can lead to catastrophic system failures. The resolution demonstrates the critical importance of maintaining unit consistency in kernel drivers, particularly when dealing with hardware interface specifications that have established conventions for property units and value representations. The fix ensures proper operation across all supported device tree configurations while preventing the deterministic kernel panic that would otherwise occur during driver initialization.