CVE-2025-68339
Unknown
Unknown - Not Provided
Data Race in Linux Kernel atm/fore200e Causes Bandwidth Misaccounting
Publication date: 2025-12-23
Last updated on: 2025-12-23
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
atm/fore200e: Fix possible data race in fore200e_open()
Protect access to fore200e->available_cell_rate with rate_mtx lock in the
error handling path of fore200e_open() to prevent a data race.
The field fore200e->available_cell_rate is a shared resource used to track
available bandwidth. It is concurrently accessed by fore200e_open(),
fore200e_close(), and fore200e_change_qos().
In fore200e_open(), the lock rate_mtx is correctly held when subtracting
vcc->qos.txtp.max_pcr from available_cell_rate to reserve bandwidth.
However, if the subsequent call to fore200e_activate_vcin() fails, the
function restores the reserved bandwidth by adding back to
available_cell_rate without holding the lock.
This introduces a race condition because available_cell_rate is a global
device resource shared across all VCCs. If the error path in
fore200e_open() executes concurrently with operations like
fore200e_close() or fore200e_change_qos() on other VCCs, a
read-modify-write race occurs.
Specifically, the error path reads the rate without the lock. If another
CPU acquires the lock and modifies the rate (e.g., releasing bandwidth in
fore200e_close()) between this read and the subsequent write, the error
path will overwrite the concurrent update with a stale value. This results
in incorrect bandwidth accounting.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
