counter: rz-mtu3-cnt: prevent counter from being toggled multiple times
Summary
counter: rz-mtu3-cnt: prevent counter from being toggled multiple times
Original description
The description as published by the source.
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.
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-31741 linux-lts Fixed in: 6.12.81-r0
- Debian DEBIAN-CVE-2026-31741 linux Fixed in: 6.12.85-1
- Ubuntu UBUNTU-CVE-2026-31741 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org