CVE-2025-38364: debian linux Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: maple_tree: fix MA_STATE_PREALLOC flag in mas_preallocate() Temporarily clear the preallocation flag when explicitly requesting allocations. Pre-existing allocations are already counted against the request through mas_node_count_gfp(), but the allocations will not happen if the MA_STATE_PREALLOC flag is set. This flag is meant to avoid re-allocating in bulk allocation mode, and to detect issues with preallocation calculations. The MA_STATE_PREALLOC flag should also always be set on zero allocations so that detection of underflow allocations will print a WARN_ON() during consumption. User visible effect of this flaw is a WARN_ON() followed by a null pointer dereference when subsequent requests for larger number of nodes is ignored, such as the vma merge retry in mmap_region() caused by drivers altering the vma flags (which happens in v6.6, at least)

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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	6.1 — 6.1.146
linux	linux_kernel	6.2 — 6.6.99
linux	linux_kernel	6.7 — 6.12.36
linux	linux_kernel	6.13 — 6.15.5
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/9e32f4700867abbd5d19abfcf698dbd0d2ce36a4 https://git.kernel.org/stable/c/cf95f8426f889949b738f51ffcd72884411f3a6a https://git.kernel.org/stable/c/d69cd64bd5af41c6fd409313504089970edaf02f https://git.kernel.org/stable/c/e63032e66bca1d06e600033f3369ba3db3af0870 https://git.kernel.org/stable/c/fba46a5d83ca8decb338722fb4899026d8d9ead2

Other References

https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html https://cert-portal.siemens.com/productcert/html/ssa-082556.html

Frequently Asked Questions

What is CVE-2025-38364? +

In the Linux kernel, the following vulnerability has been resolved: maple_tree: fix MA_STATE_PREALLOC flag in mas_preallocate() Temporarily clear the preallocation flag when explicitly requesting allocations. Pre-existing allocations are already counted against the request through mas_node_count_gfp(), but the allocations will not happen if the MA_STATE_PREALLOC flag is set. This flag is meant to avoid re-allocating in bulk allocation mode, and to detect issues with preallocation calculations. The MA_STATE_PREALLOC flag should also always be set on zero allocations so that detection of underflow allocations will print a WARN_ON() during consumption. User visible effect of this flaw is a WARN_ON() followed by a null pointer dereference when subsequent requests for larger number of nodes is ignored, such as the vma merge retry in mmap_region() caused by drivers altering the vma flags (which happens in v6.6, at least) It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38364? +

CVE-2025-38364 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-2025-38364? +

CVE-2025-38364 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-2025-38364? +

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-2025-38364