CVE-2025-39713

/// Technical 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 t

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References