CVE-2025-21799: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: ti: am65-cpsw: fix freeing IRQ in am65_cpsw_nuss_remove_tx_chns() When getting the IRQ we use k3_udma_glue_tx_get_irq() which returns negative error value on error. So not NULL check is not sufficient to deteremine if IRQ is valid. Check that IRQ is greater then zero to ensure it is valid. There is no issue at probe time but at runtime user can invoke .set_channels which results in the following call chain. am65_cpsw_set_channels() am65_cpsw_nuss_update_tx_rx_chns() am65_cpsw_nuss_remove_tx_chns() am65_cpsw_nuss_init_tx_chns() At this point if am65_cpsw_nuss_init_tx_chns() fails due to k3_udma_glue_tx_get_irq() then tx_chn->irq will be set to a negative value. Then, at subsequent .set_channels with higher channel count we will attempt to free an invalid IRQ in am65_cpsw_nuss_remove_tx_chns() leading to a kernel warning. The issue is present in the original commit that introduced this driver, although there, am65_cpsw_nuss_update_tx_rx_chns() existed as am65_cpsw_nuss_update_tx_chns().

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CVSS v3.1 Score

5.5

MEDIUM

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

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.7 — 5.10.235
linux	linux_kernel	5.11 — 5.15.179
linux	linux_kernel	5.16 — 6.1.129
linux	linux_kernel	6.2 — 6.6.76
linux	linux_kernel	6.7 — 6.12.13
linux	linux_kernel	6.13 — 6.13.2

References

Advisories & Patches

https://git.kernel.org/stable/c/321990fdf4f1bb64e818c7140688bf33d129e48d https://git.kernel.org/stable/c/4395a44acb15850e492dd1de9ec4b6479d96bc80 https://git.kernel.org/stable/c/8448c87b3af68bebca21e3136913f7f77e363515 https://git.kernel.org/stable/c/88fd5db8c0073bd91d18391feb5741aeb0a2b475 https://git.kernel.org/stable/c/8aae91ae1c65782a169ec070e023d4d269e5d6e6 https://git.kernel.org/stable/c/aea5cca681d268f794fa2385f9ec26a5cce025cd https://git.kernel.org/stable/c/ed8c0300f302338c36edb06bca99051e5be6fb2f

Other References

https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html

Frequently Asked Questions

What is CVE-2025-21799? +

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: ti: am65-cpsw: fix freeing IRQ in am65_cpsw_nuss_remove_tx_chns() When getting the IRQ we use k3_udma_glue_tx_get_irq() which returns negative error value on error. So not NULL check is not sufficient to deteremine if IRQ is valid. Check that IRQ is greater then zero to ensure it is valid. There is no issue at probe time but at runtime user can invoke .set_channels which results in the following call chain. am65_cpsw_set_channels() am65_cpsw_nuss_update_tx_rx_chns() am65_cpsw_nuss_remove_tx_chns() am65_cpsw_nuss_init_tx_chns() At this point if am65_cpsw_nuss_init_tx_chns() fails due to k3_udma_glue_tx_get_irq() then tx_chn->irq will be set to a negative value. Then, at subsequent .set_channels with higher channel count we will attempt to free an invalid IRQ in am65_cpsw_nuss_remove_tx_chns() leading to a kernel warning. The issue is present in the original commit that introduced this driver, although there, am65_cpsw_nuss_update_tx_rx_chns() existed as am65_cpsw_nuss_update_tx_chns(). It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21799? +

CVE-2025-21799 has a CVSS v3.1 score of 5.5 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-2025-21799? +

CVE-2025-21799 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21799? +

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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CVE-2025-21799