In the Linux kernel, the following vulnerability has been resolved:

counter: rz-mtu3-cnt: prevent counter from being toggled multiple times

Runtime PM counter is incremented / decremented each time the sysfs
enable file is written to.

If user writes 0 to the sysfs enable file multiple times, runtime PM
usage count underflows, generating the following message.

rz-mtu3-counter rz-mtu3-counter.0: Runtime PM usage count underflow!

At the same time, hardware registers end up being accessed with clocks
off in rz_mtu3_terminate_counter() to disable an already disabled
channel.

If user writes 1 to the sysfs enable file multiple times, runtime PM
usage count will be incremented each time, requiring the same number of
0 writes to get it back to 0.

If user writes 0 to the sysfs enable file while PWM is in progress, PWM
is stopped without counter being the owner of the underlying MTU3
channel.

Check against the cached count_is_enabled value and exit if the user
is trying to set the same enable value.

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History

Fri, 01 May 2026 14:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: counter: rz-mtu3-cnt: prevent counter from being toggled multiple times Runtime PM counter is incremented / decremented each time the sysfs enable file is written to. If user writes 0 to the sysfs enable file multiple times, runtime PM usage count underflows, generating the following message. rz-mtu3-counter rz-mtu3-counter.0: Runtime PM usage count underflow! At the same time, hardware registers end up being accessed with clocks off in rz_mtu3_terminate_counter() to disable an already disabled channel. If user writes 1 to the sysfs enable file multiple times, runtime PM usage count will be incremented each time, requiring the same number of 0 writes to get it back to 0. If user writes 0 to the sysfs enable file while PWM is in progress, PWM is stopped without counter being the owner of the underlying MTU3 channel. Check against the cached count_is_enabled value and exit if the user is trying to set the same enable value.
Title counter: rz-mtu3-cnt: prevent counter from being toggled multiple times
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-01T14:14:36.845Z

Reserved: 2026-03-09T15:48:24.138Z

Link: CVE-2026-31741

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-01T15:16:36.820

Modified: 2026-05-01T15:24:14.893

Link: CVE-2026-31741

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-01T16:30:20Z

Weaknesses

No weakness.