CVE-2025-37787: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: net: dsa: mv88e6xxx: avoid unregistering devlink regions which were never registered Russell King reports that a system with mv88e6xxx dereferences a NULL pointer when unbinding this driver: https://lore.kernel.org/netdev/[email protected]/ The crash seems to be in devlink_region_destroy(), which is not NULL tolerant but is given a NULL devlink global region pointer. At least on some chips, some devlink regions are conditionally registered since the blamed commit, see mv88e6xxx_setup_devlink_regions_global(): if (cond && !cond(chip)) continue; These are MV88E6XXX_REGION_STU and MV88E6XXX_REGION_PVT. If the chip does not have an STU or PVT, it should crash like this. To fix the issue, avoid unregistering those regions which are NULL, i.e. were skipped at mv88e6xxx_setup_devlink_regions_global() time.

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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	5.13 — 5.15.181
linux	linux_kernel	5.16 — 6.1.135
linux	linux_kernel	6.2 — 6.6.88
linux	linux_kernel	6.7 — 6.12.25
linux	linux_kernel	6.13 — 6.14.4
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/3665695e3572239dc233216f06b41f40cc771889 https://git.kernel.org/stable/c/5f5e95945bb1e08be7655da6acba648274db457d https://git.kernel.org/stable/c/8ccdf5e24b276848eefb2755e05ff0f005a0c4a1 https://git.kernel.org/stable/c/b3c70dfe51f10df60db2646c08cebd24bcdc5247 https://git.kernel.org/stable/c/bbb80f004f7a90c3dcaacc982c59967457254a05 https://git.kernel.org/stable/c/c84f6ce918a9e6f4996597cbc62536bbf2247c96

Other References

https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

Frequently Asked Questions

What is CVE-2025-37787? +

In the Linux kernel, the following vulnerability has been resolved: net: dsa: mv88e6xxx: avoid unregistering devlink regions which were never registered Russell King reports that a system with mv88e6xxx dereferences a NULL pointer when unbinding this driver: https://lore.kernel.org/netdev/[email protected]/ The crash seems to be in devlink_region_destroy(), which is not NULL tolerant but is given a NULL devlink global region pointer. At least on some chips, some devlink regions are conditionally registered since the blamed commit, see mv88e6xxx_setup_devlink_regions_global(): if (cond && !cond(chip)) continue; These are MV88E6XXX_REGION_STU and MV88E6XXX_REGION_PVT. If the chip does not have an STU or PVT, it should crash like this. To fix the issue, avoid unregistering those regions which are NULL, i.e. were skipped at mv88e6xxx_setup_devlink_regions_global() time. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-37787? +

CVE-2025-37787 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-2025-37787? +

CVE-2025-37787 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-2025-37787? +

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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