CVE-2025-40209

Ecosystem	Package	Version

Vulnerabilities

CVE-2025-40209

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory leak of qgroup_list in btrfs_add_qgroup_relation When btrfs_add_qgroup_relation() is called with invalid qgroup levels (src >= dst), the function returns -EINVAL directly without freeing the preallocated qgroup_list structure passed by the caller. This causes a memory leak because the caller unconditionally sets the pointer to NULL after the call, preventing any cleanup. The issue occurs because the level validation check happens before the mutex is acquired and before any error handling path that would free the prealloc pointer. On this early return, the cleanup code at the 'out' label (which includes kfree(prealloc)) is never reached. In btrfs_ioctl_qgroup_assign(), the code pattern is: prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL); ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst, prealloc); prealloc = NULL; // Always set to NULL regardless of return value ... kfree(prealloc); // This becomes kfree(NULL), does nothing When the level check fails, 'prealloc' is never freed by either the callee or the caller, resulting in a 64-byte memory leak per failed operation. This can be triggered repeatedly by an unprivileged user with access to a writable btrfs mount, potentially exhausting kernel memory. Fix this by freeing prealloc before the early return, ensuring prealloc is always freed on all error paths.

Published Nov 21, 2025

https://lore.kernel.org/linux-cve-announce/2025112105-CVE-2025-40209-b7cb@gregkh/

CVSS ScoreMedium

6.8


rpm	kernel	6.11.0-0.rc5.23.el10
rpm	kernel	6.12.0-124.13.1.el10_1
rpm	kernel	6.12.0-124.16.1.el10_1
rpm	kernel	6.12.0-124.20.1.el10_1
rpm	kernel	6.12.0-124.21.1.el10_1
rpm	kernel	6.12.0-124.27.1.el10_1
rpm	kernel	6.12.0-124.28.1.el10_1
rpm	kernel	6.12.0-124.29.1.el10_1
rpm	kernel	6.12.0-124.31.1.el10_1
rpm	kernel	6.12.0-124.35.1.el10_1
rpm	kernel	6.12.0-124.38.1.el10_1
rpm	kernel	6.12.0-124.39.1.el10_1
rpm	kernel	6.12.0-124.40.1.el10_1
rpm	kernel	6.12.0-124.8.1.el10_1
rpm	kernel	6.12.0-55.19.1.0.1.el10_0
rpm	kernel	6.12.0-55.20.1.0.1.el10_0
rpm	kernel	6.12.0-55.21.1.0.1.el10_0
rpm	kernel	6.12.0-55.22.1.0.1.el10_0
rpm	kernel	6.12.0-55.24.1.0.1.el10_0
rpm	kernel	6.12.0-55.27.1.0.1.el10_0
rpm	kernel	6.12.0-55.28.1.0.1.el10_0
rpm	kernel	6.12.0-55.29.1.0.1.el10_0
rpm	kernel	6.12.0-55.30.1.0.1.el10_0
rpm	kernel	6.12.0-55.31.1.0.1.el10_0
rpm	kernel	6.12.0-55.32.1.0.1.el10_0
rpm	kernel	6.12.0-55.33.1.0.1.el10_0
rpm	kernel	6.12.0-55.34.1.0.1.el10_0
rpm	kernel	6.12.0-55.37.1.0.1.el10_0
rpm	kernel	6.12.0-55.38.1.0.1.el10_0
rpm	kernel	6.12.0-55.39.1.0.1.el10_0
rpm	kernel	6.12.0-55.40.1.0.1.el10_0
rpm	kernel	6.12.0-55.41.1.0.1.el10_0
rpm	kernel	6.12.0-55.42.1.0.1.el10_0
rpm	kernel	6.12.0-55.43.1.0.1.el10_0
rpm	kernel	6.12.0-55.9.1.0.1.el10_0

Ecosystem	Package	Version

CVE-2025-40209 | Components Impacted | Sonatype Guide | Sonatype Guide

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CVE-2025-40209