CVE-2026-64498 Overview
CVE-2026-64498 is a memory leak vulnerability in the Linux kernel's Industrial I/O (IIO) subsystem. The flaw resides in the hardware consumer buffer implementation, specifically in the iio_hw_buf_release() function. When an IIO hardware consumer buffer is released, the scan_mask bitmap allocation is not freed, resulting in leaked kernel memory each time the buffer is torn down.
Critical Impact
The vulnerability causes kernel memory leaks on IIO hardware consumer buffer release, which can degrade system stability over time on affected Linux systems using IIO devices.
Affected Products
- Linux kernel versions containing commit 9a2e1233d38c ("iio: buffer: hw-consumer: remove redundant scan_mask flexible array")
- Linux kernel IIO (Industrial I/O) subsystem
- Systems utilizing IIO hardware consumer buffers
Discovery Timeline
- 2026-07-25 - CVE-2026-64498 published to NVD
- 2026-07-25 - Last updated in NVD database
Technical Details for CVE-2026-64498
Vulnerability Analysis
The vulnerability affects the Linux kernel's IIO buffer hardware consumer implementation. The scan_mask field is used to indicate which channels of an IIO device are enabled for data capture. Prior to the referenced refactoring, the scan mask storage was embedded directly within struct hw_consumer_buffer, meaning iio_hw_buf_release() could reclaim the entire allocation through a single kfree(hw_buf) call.
Commit 9a2e1233d38c refactored this design by moving the scan mask into a separate allocation created via bitmap_zalloc() and stored in buffer.scan_mask. The refactor did not update the release path. As a result, iio_hw_buf_release() continues to free only the buffer wrapper, leaving the separately allocated bitmap orphaned in kernel memory.
Root Cause
The root cause is an incomplete refactor. When scan_mask was moved from an embedded flexible array to a standalone bitmap_zalloc() allocation, the corresponding cleanup logic in iio_hw_buf_release() was not updated to free the new allocation. This is a classic memory leak pattern where allocation and deallocation code paths diverge after a data structure change.
Attack Vector
The attack surface is limited to local operations that trigger IIO hardware consumer buffer allocation and release cycles. Each buffer release leaks the scan mask bitmap. Repeated allocation and release operations on IIO devices can accumulate leaked kernel memory over time, contributing to resource exhaustion on long-running systems with IIO workloads.
The fix ensures the scan mask is freed in iio_hw_buf_release() before the buffer wrapper itself is released. Full patch details are available in the kernel commit history and the follow-up fix commit.
Detection Methods for CVE-2026-64498
Indicators of Compromise
- Gradual increase in kernel slab memory usage on systems using IIO hardware consumer buffers
- Elevated bitmap_zalloc allocation counts without corresponding frees visible in kernel memory tracing
- System instability or out-of-memory conditions correlated with IIO device usage cycles
Detection Strategies
- Audit installed kernel versions against the fix commits 6325d6e2204327965b849c0a16efb6ac9202e5a8 and fb8e18f8ca724bd4de4643cad5b7c7230b9a5a71
- Use kmemleak kernel debugging to identify unreleased bitmap allocations tied to IIO buffer teardown paths
- Monitor /proc/meminfo and /proc/slabinfo for anomalous kernel memory growth over extended runtime
Monitoring Recommendations
- Track kernel memory consumption on hosts that instantiate IIO devices through industrial sensors or ADC hardware
- Enable kernel tracing on iio_hw_buf_release to observe buffer release frequency
- Aggregate host telemetry into a centralized observability platform to correlate memory growth with device activity
How to Mitigate CVE-2026-64498
Immediate Actions Required
- Identify all Linux systems running kernel builds that include commit 9a2e1233d38c but not the fix commits
- Apply the upstream stable kernel patches referenced in the kernel.org commit history
- Reboot patched systems to load the corrected kernel module code paths
Patch Information
The upstream fix modifies iio_hw_buf_release() to explicitly free the scan_mask bitmap allocation before releasing the buffer wrapper. Fixed code is present in the referenced kernel commits merged into stable kernel branches. Distribution maintainers backport these fixes into their supported kernel releases; consult your vendor's advisories for specific package versions.
Workarounds
- Limit unnecessary allocation and release cycles of IIO hardware consumer buffers on unpatched hosts
- Schedule periodic reboots on long-running systems that cannot be immediately patched to reclaim leaked kernel memory
- Restrict access to IIO device interfaces to reduce the frequency of buffer teardown operations
# Verify running kernel version and check for IIO subsystem usage
uname -r
lsmod | grep industrialio
dmesg | grep -i iio
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
