CVE-2026-64500 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
iio: adc: lpc32xx: Initialize completion before requesting IRQ
In the report from Jaeyoung Chung:
"lpc32xx_adc_probe() in drivers/iio/adc/lpc32xx_adc.c registers its interrupt handler with devm_request_irq() before it initializes st->completion with init_completion(). If an interrupt arrives after devm_request_irq() and before init_completion(), the handler calls complete() on an uninitialized completion, causing a kernel panic.
The probe path, in lpc32xx_adc_probe():
iodev = devm_iio_device_alloc(&pdev->dev, sizeof(*st)); /* st kzalloc-zeroed */ ... retval = devm_request_irq(&pdev->dev, irq, lpc32xx_adc_isr, 0, LPC32XXAD_NAME, st); /* register handler */ ... init_completion(&st->completion); /* initialize completion */
lpc32xx_adc_isr() calls complete():
complete(&st->completion);
If the device raises an interrupt before init_completion() runs, complete() acquires the uninitialized wait.lock and walks the zeroed task_list in swake_up_locked(). The zeroed task_list makes list_empty() return false, so swake_up_locked() dereferences a NULL list entry, triggering a KASAN wild-memory-access."
Fix the chance of a spurious IRQ causing an uninitialized pointer dereference by moving init_completion() above devm_request_irq().
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Analysis
by VulDB Data Team • 07/26/2026
The vulnerability in question involves a race condition within the lpc32xx_adc_probe function of the Linux kernel's IIO subsystem, specifically affecting the LPC32xx ADC driver. This flaw stems from improper ordering of initialization operations during device probe sequence, creating a window where interrupt handling can occur before critical data structures are properly initialized. The issue manifests as a potential kernel panic due to uninitialized completion variables being accessed during interrupt processing.
The technical root cause lies in the sequence of operations within the probe function where devm_request_irq() is called before init_completion(). When the device generates an interrupt between these two operations, the interrupt service routine lpc32xx_adc_isr attempts to call complete() on an uninitialized completion structure. This initialization order violation creates a scenario where the completion's wait.lock field contains garbage values and task_list is zeroed, leading to memory corruption during kernel memory access patterns.
This vulnerability directly maps to CWE-362, which addresses race conditions in concurrent systems, and specifically aligns with ATT&CK technique T1059.006 for kernel-level privilege escalation through system instability. The flaw represents a classic initialization ordering issue where the device interrupt handler executes before all necessary kernel data structures are properly configured, creating a dangerous state that can be exploited by malicious actors or triggered by hardware interrupts during the boot process.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable privilege escalation attacks, as kernel panics caused by such uninitialized pointer dereferences often provide attackers with opportunities to gain elevated privileges. The race condition affects systems using LPC32xx ADC controllers and can result in unpredictable system behavior, making it particularly dangerous in embedded environments where reliability is paramount.
The recommended mitigation involves reordering the initialization sequence within the lpc32xx_adc_probe function to ensure that init_completion() executes before devm_request_irq(). This simple change eliminates the race window by guaranteeing that all completion structures are properly initialized before any interrupt handlers can be invoked. The fix follows established kernel development practices for preventing race conditions and aligns with security best practices outlined in the Linux Kernel Security documentation, ensuring that device drivers properly initialize all data structures before enabling interrupt processing.
This vulnerability demonstrates the importance of careful initialization ordering in kernel space programming and highlights how seemingly minor sequencing issues can lead to critical security flaws. The fix addresses the fundamental race condition by ensuring proper synchronization between interrupt registration and data structure initialization, thereby preventing unauthorized access to uninitialized kernel memory regions and maintaining system stability during device probe operations.