CVE-2025-39713: debian linux — Fix

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.

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CVSS v3.1 Score

4.7

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-367 CWE-367

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.12 — 5.4.297
linux	linux_kernel	5.5 — 5.10.241
linux	linux_kernel	5.11 — 5.15.190
linux	linux_kernel	5.16 — 6.1.149
linux	linux_kernel	6.2 — 6.6.103
linux	linux_kernel	6.7 — 6.12.44
linux	linux_kernel	6.13 — 6.16.4
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/1c2769dc80255824542ea5a4ff1a07dcdeb1603f https://git.kernel.org/stable/c/2964dbe631fd21ad7873b1752b895548d3c12496 https://git.kernel.org/stable/c/3c3e33b7edca7a2d6a96801f287f9faeb684d655 https://git.kernel.org/stable/c/6aaef1a75985865d8c6c5b65fb54152060faba48 https://git.kernel.org/stable/c/7af160aea26c7dc9e6734d19306128cce156ec40 https://git.kernel.org/stable/c/ed905fe7cba03cf22ae0b84cf1b73cd1c070423a https://git.kernel.org/stable/c/fbc81e78d75bf28972bc22b1599559557b1a1b83 https://git.kernel.org/stable/c/ff9dd3db6cd4c6b54a2ecbc58151bea4ec63bc59

Other References

https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html https://cert-portal.siemens.com/productcert/html/ssa-032379.html

Frequently Asked Questions

What is CVE-2025-39713? +

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. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2025-39713? +

CVE-2025-39713 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-39713? +

CVE-2025-39713 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-39713? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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