CVE-2026-64501
Received Received - Intake

Use After Free in Linux Kernel IIO ADC Sigma Delta Driver

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: iio: adc: ad_sigma_delta: fix CS held asserted and state leaks In ad_sigma_delta_single_conversion(), set_mode(AD_SD_MODE_IDLE) and disable_one() were called from the out: block while keep_cs_asserted was still true. This caused any SPI transfer issued by those callbacks to carry cs_change=1, leaving CS permanently asserted after the conversion. Fix by moving both calls into the out_unlock: block, after keep_cs_asserted is cleared, matching the pattern already used in ad_sd_calibrate(). In the error path of ad_sd_buffer_postenable(), if an operation fails after set_mode(AD_SD_MODE_CONTINUOUS) has already succeeded (e.g. spi_offload_trigger_enable()), the device is left in continuous conversion mode with CS physically asserted. Additionally, bus_locked remaining true after spi_bus_unlock() causes subsequent SPI operations to call spi_sync_locked() without the bus lock actually held, allowing concurrent SPI access. Fix the error path by clearing keep_cs_asserted first, then calling set_mode(AD_SD_MODE_IDLE) to revert the device mode and deassert CS, then clearing bus_locked before releasing the bus. For devices that implement neither set_mode nor disable_one (such as MAX11205, which has no physical CS pin), no SPI transfer is issued during cleanup and the cs_change flag has no effect on any physical line.

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64501
EUVD
EUVD-2026-48845

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves incorrect handling of SPI chip select (CS) signals in ADC drivers. It causes the CS line to remain asserted after operations, leading to SPI transfers with cs_change=1. This leaves the device in an inconsistent state where CS is permanently asserted or conversion modes are not properly reset.

Detection Guidance

This vulnerability is specific to the Linux kernel's IIO ADC subsystem and SPI device interactions. Detection requires checking kernel logs for SPI-related errors or unexpected CS (Chip Select) behavior during ADC operations. Monitor dmesg for errors like 'SPI transfer failed' or 'CS held asserted' after conversions. No direct network detection is applicable as this is a local kernel issue.

Impact Analysis

The vulnerability can cause SPI devices to malfunction due to incorrect CS line behavior. It may lead to data corruption, device lockups, or unexpected behavior in systems using affected ADC drivers. Systems relying on proper SPI communication could experience failures or reduced reliability.

Mitigation Strategies

Apply the latest Linux kernel update that includes the fix for CVE-2026-64501. If immediate patching is not possible, avoid using affected ADC devices (e.g., MAX11205) in continuous conversion mode. Monitor SPI bus activity for CS line issues and restrict access to SPI devices until patched.

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