CVE-2025-71185: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-71185 is a device reference leak vulnerability in the Linux kernel's dmaengine: ti: dma-crossbar driver affecting AM335x-based systems. The flaw occurs during route allocation when a reference taken while looking up the crossbar platform device is never released, resulting in a kernel memory leak. It was published on January 31, 2026, and affects Linux kernel versions from 4.4 through multiple stable branches up to 6.18.x and 6.19-rc releases. The vulnerability carries a CVSS v3.1 base score of 5.5 (Medium) (Red Hat Advisory, Red Hat Bugzilla).

The root cause is classified as CWE-401 (Missing Release of Memory after Effective Lifetime). During AM335x DMA crossbar route allocation, the kernel calls a platform device lookup function that increments a reference count on the crossbar device object, but the corresponding put_device() call to decrement that reference is never made, leaving the reference permanently held. This is a local vulnerability requiring low privileges (e.g., a process that triggers DMA crossbar route allocation), with no user interaction needed. The fix, integrated into stable kernel trees, ensures the reference is properly dropped after the lookup completes (Red Hat Bugzilla, Feedly).

The primary impact is a denial of service (DoS) condition affecting system availability. Repeated triggering of AM335x DMA crossbar route allocation causes unreleased device references to accumulate, gradually exhausting kernel memory resources and potentially rendering the system unresponsive. There is no confidentiality or integrity impact; the vulnerability is limited to availability degradation on systems using the TI AM335x SoC DMA crossbar hardware (Feedly).

Update the Linux kernel to a patched stable version: 5.10.249 or later (for 4.4–5.10 branch), 5.15.199 or later (5.11–5.15), 6.1.162 or later (5.16–6.1), 6.6.122 or later (6.2–6.6), 6.12.67 or later (6.7–6.12), or 6.18.7 or later (6.13+). Ubuntu security notices USN-8162-1, USN-8180-x, USN-8186-1, USN-8188-1, USN-8275-1, USN-8278-x, USN-8289-x, USN-8296-x, USN-8297-1, and USN-8393-1 address this issue for various Ubuntu kernel flavors. As a compensating control, restrict local user access on systems running affected kernels with AM335x DMA crossbar hardware to reduce exposure (Red Hat Bugzilla, Ubuntu USN-8180-1).