CVE-2026-89888 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
media: i2c: ov02a10: fix endpoint parsing use-after-free
The ov02a10_check_hwcfg() function calls fwnode_handle_put(ep) immediately after allocating and parsing the endpoint. However, it subsequently calls fwnode_property_read_u32() using the same 'ep' handle, leading to a potential use-after-free.
Additionally, reading the optional 'ovti,mipi-clock-voltage' property used to overwrite the 'ret' variable. If the property was missing, 'ret' would become negative, and this failure code would be incorrectly returned at the end of the function, causing probe to fail entirely.
Fix the use-after-free by moving fwnode_property_read_u32() before the endpoint is parsed and freed. Avoid the error leak by not assigning the result of fwnode_property_read_u32() to 'ret'.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in the Linux kernel media subsystem involves a critical use-after-free condition within the ov02a10 camera sensor driver, specifically located in the ov02a10_check_hwcfg function. This flaw arises from an incorrect sequence of operations during hardware configuration validation and endpoint parsing. The core issue stems from the premature release of firmware node handles before all necessary data has been extracted from them. In Linux kernel development, firmware nodes represent device tree or ACPI entries that describe hardware properties. These nodes are reference-counted resources that must be managed carefully to prevent memory corruption. When a driver allocates and parses an endpoint handle using fwnode_handle_get, it assumes ownership of that resource until it explicitly releases it via fwnode_handle_put. The vulnerability occurs because the code invokes fwnode_handle_put on the ep pointer immediately after initial parsing steps are completed, but before subsequent property reads are executed against that same pointer.
This sequence error leads to a classic use-after-free scenario classified under CWE-416 in the Common Weakness Enumeration framework. After the endpoint handle is freed, any attempt to access it results in undefined behavior. In this specific implementation, the code subsequently calls fwnode_property_read_u32 using the now-dangling ep pointer. If the memory previously occupied by the firmware node structure has been reallocated for a different purpose or if the kernel's slab allocator returns an error due to invalid state, accessing this freed memory can lead to data corruption, kernel panics, or potentially exploitable conditions where an attacker might influence control flow through carefully crafted device tree configurations. The severity of such vulnerabilities is often elevated in kernel space because they bypass user-space protections and operate with full system privileges, making them attractive targets for privilege escalation attacks mapped under MITRE ATT&CK technique T1068 Exploitation for Privilege Escalation when combined with other local vector weaknesses.
Beyond the memory safety issue, there is a secondary logic flaw related to error handling that causes functional regressions in device initialization. The function attempts to read an optional property named ovti,mipi-clock-voltage using fwnode_property_read_u32. This API returns zero on success and a negative error code if the property does not exist or cannot be read. In the flawed implementation, the return value of this call was directly assigned to the ret variable used for tracking overall function status. Since the property is optional, its absence results in fwnode_property_read_u32 returning an error code such as -EINVAL or -ENOENT. This negative value overwrites any previous success state stored in ret, causing the entire probe routine to fail even when all critical hardware configurations are valid. This represents a logic error classified under CWE-754 Improper Check for Unusual or Exceptional Conditions, where optional configuration parameters are treated as mandatory requirements due to improper handling of return codes.
The operational impact of this vulnerability is twofold: system instability and device unavailability. The use-after-free condition poses a risk to kernel stability, potentially causing crashes that require a full reboot if triggered by malicious or malformed hardware descriptions. For legitimate users, the error handling bug prevents the ov02a10 sensor from initializing correctly on many systems where the optional voltage property is not defined in the device tree. This results in cameras failing to appear as functional devices within the operating system, disrupting multimedia applications and security monitoring infrastructure that rely on these sensors. The combination of memory corruption risks and denial-of-service through probe failures makes this a significant issue requiring immediate remediation.
The resolution involves restructuring the code flow to ensure proper resource lifecycle management and correcting the error propagation logic. First, all property reads using fwnode_property_read_u32 are moved before the call to fwnode_handle_put for the endpoint handle. This ensures that the firmware node is still valid when accessed, eliminating the use-after-free condition entirely. Second, the assignment of the return value from optional property reads to the ret variable is removed or modified to ignore non-critical errors. By decoupling the success status of mandatory checks from optional configuration lookups, the driver correctly distinguishes between fatal initialization failures and benign missing properties. This fix aligns with best practices for kernel memory management as outlined in Linux kernel documentation regarding firmware node handling and ensures compliance with robust error handling patterns recommended by industry standards.
Mitigation strategies beyond applying this patch include ensuring that all media drivers adhere to strict reference counting protocols where handles are only released after every access is complete. Developers should audit similar code paths in other sensor drivers for analogous patterns of premature deallocation. Additionally, static analysis tools and fuzzing frameworks can be employed to detect use-after-free conditions early in the development cycle. For system administrators unable to apply patches immediately, restricting hardware configuration inputs or disabling affected devices via device tree overlays may reduce exposure until updates are deployed. Maintaining up-to-date kernel versions remains the most effective defense against such low-level memory safety vulnerabilities that exploit complex resource management logic within the operating system core.