CVE-2026-72118
Received Received - Intake

Race Condition in Linux Kernel CAN BCM Module

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: can: bcm: fix CAN frame rx/tx statistics KCSAN detected a data race within the bcm_rx_handler() when two CAN frames have been simultaneously received and processed in a single rx op by two different CPUs. Use atomic operations with (signed) long data types to access the statistics in the hot path to fix the KCSAN complaint. Additionally simplify the update and check of statistics overflow by using the atomic operations in separate bcm_update_[rx|tx]_stats() functions. The rx variant runs under bcm_rx_update_lock to prevent races when resetting the two rx counters; the tx variant runs under bcm_tx_lock and only needs to guard its own counter's overflow. As the rx path resets its values already at LONG_MAX / 100, there is no conflict between the two locking domains (bcm_rx_update_lock vs. bcm_tx_lock) even for ops that use both paths. The rx statistics update and the frames_filtered update in bcm_rx_changed() were previously performed in two separate bcm_rx_update_lock sections. For an rx op subscribed on all interfaces (ifindex == 0), bcm_rx_handler() can run concurrently on different CPUs, so a counter reset by one CPU between these two sections could leave frames_filtered larger than frames_abs on another CPU, producing a bogus (even negative) reduction percentage in procfs. Update the statistics in the same critical section as bcm_rx_changed() to close this gap, which also removes the now unneeded extra lock/unlock pair around the traffic_flags calculation.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-72118
EUVD
EUVD-2026-59076

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel 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 a data race in the CAN (Controller Area Network) BCM (Broadcast Manager) module. When two CAN frames are received simultaneously and processed by different CPUs, a race condition occurs in the bcm_rx_handler() function. The issue arises from unsynchronized access to statistics counters, which can lead to incorrect or corrupted data.

Detection Guidance

This vulnerability is specific to the Linux kernel's CAN bus module (bcm) and involves a data race in CAN frame statistics handling. Detection requires checking kernel logs for KCSAN warnings related to CAN frame processing or examining kernel source code for the affected bcm module. No direct commands are provided in the context to detect this issue.

Impact Analysis

The vulnerability may cause incorrect CAN frame statistics to be reported, potentially leading to misinformation about network traffic. While it does not directly cause system crashes or data corruption, it could affect monitoring and debugging processes that rely on accurate CAN frame counts.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. Update your kernel to a version containing the fix for the CAN bcm module data race. Monitor kernel logs for CAN-related errors or warnings after applying updates.

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