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

media: rainshadow-cec: fix TOCTOU race condition in rain_interrupt()

In the interrupt handler rain_interrupt(), the buffer full check on
rain->buf_len is performed before acquiring rain->buf_lock. This
creates a Time-of-Check to Time-of-Use (TOCTOU) race condition, as
rain->buf_len is concurrently accessed and modified in the work
handler rain_irq_work_handler() under the same lock.

Multiple interrupt invocations can race, with each reading buf_len
before it becomes full and then proceeding. This can lead to both
interrupts attempting to write to the buffer, incrementing buf_len
beyond its capacity (DATA_SIZE) and causing a buffer overflow.

Fix this bug by moving the spin_lock() to before the buffer full
check. This ensures that the check and the subsequent buffer modification
are performed atomically, preventing the race condition. An corresponding
spin_unlock() is added to the overflow path to correctly release the
lock.

This possible bug was found by an experimental static analysis tool
developed by our team.
History

Fri, 05 Sep 2025 17:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: media: rainshadow-cec: fix TOCTOU race condition in rain_interrupt() In the interrupt handler rain_interrupt(), the buffer full check on rain->buf_len is performed before acquiring rain->buf_lock. This creates a Time-of-Check to Time-of-Use (TOCTOU) race condition, as rain->buf_len is concurrently accessed and modified in the work handler rain_irq_work_handler() under the same lock. Multiple interrupt invocations can race, with each reading buf_len before it becomes full and then proceeding. This can lead to both interrupts attempting to write to the buffer, incrementing buf_len beyond its capacity (DATA_SIZE) and causing a buffer overflow. Fix this bug by moving the spin_lock() to before the buffer full check. This ensures that the check and the subsequent buffer modification are performed atomically, preventing the race condition. An corresponding spin_unlock() is added to the overflow path to correctly release the lock. This possible bug was found by an experimental static analysis tool developed by our team.
Title media: rainshadow-cec: fix TOCTOU race condition in rain_interrupt()
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-09-05T17:21:20.459Z

Reserved: 2025-04-16T07:20:57.116Z

Link: CVE-2025-39713

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2025-09-05T18:15:48.720

Modified: 2025-09-05T18:15:48.720

Link: CVE-2025-39713

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.