CVE-2025-37875 igc: fix PTM cycle trigger logic

What is CVE-2025-37875?

CVE-2025-37875 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 9 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

igc: fix PTM cycle trigger logic

Writing to clear the PTM status 'valid' bit while the PTM cycle is triggered results in unreliable PTM operation. To fix this, clear the PTM 'trigger' and status after each PTM transaction.

The issue can be reproduced with the following:

$ sudo phc2sys -R 1000 -O 0 -i tsn0 -m

Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to quickly reproduce the issue.

PHC2SYS exits with:

"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction fails

This patch also fixes a hang in igc_probe() when loading the igc driver in the kdump kernel on systems supporting PTM.

The igc driver running in the base kernel enables PTM trigger in igc_probe(). Therefore the driver is always in PTM trigger mode, except in brief periods when manually triggering a PTM cycle.

When a crash occurs, the NIC is reset while PTM trigger is enabled. Due to a hardware problem, the NIC is subsequently in a bad busmaster state and doesn't handle register reads/writes. When running igc_probe() in the kdump kernel, the first register access to a NIC register hangs driver probing and ultimately breaks kdump.

With this patch, igc has PTM trigger disabled most of the time, and the trigger is only enabled for very brief (10 - 100 us) periods when manually triggering a PTM cycle. Chances that a crash occurs during a PTM trigger are not 0, but extremely reduced.

Which versions are affected by CVE-2025-37875?

It affects 2 products.

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2025-37875?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-37875 being exploited?

There is no known exploitation of CVE-2025-37875 in the wild and no public exploit code.

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All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-37875, DEBIAN-CVE-2025-37875, GHSA-8rhv-v35f-jq29, ROOT-OS-DEBIAN-12-CVE-2025-37875, ROOT-OS-UBUNTU-2204-CVE-2025-37875, ROOT-OS-UBUNTU-2404-CVE-2025-37875 and 1 more.