CVE-2025-37989

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

net: phy: leds: fix memory leak

A network restart test on a router led to an out-of-memory condition, which was traced to a memory leak in the PHY LED trigger code.

The root cause is misuse of the devm API. The registration function (phy_led_triggers_register) is called from phy_attach_direct, not phy_probe, and the unregister function (phy_led_triggers_unregister) is called from phy_detach, not phy_remove. This means the register and unregister functions can be called multiple times for the same PHY device, but devm-allocated memory is not freed until the driver is unbound.

This also prevents kmemleak from detecting the leak, as the devm API internally stores the allocated pointer.

Fix this by replacing devm_kzalloc/devm_kcalloc with standard kzalloc/kcalloc, and add the corresponding kfree calls in the unregister path.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/41143e71052a00d654c15dc924fda50c1e7357d0
• https://git.kernel.org/stable/c/618541a6cc1511064dfa58c89b3445e21844092f
• https://git.kernel.org/stable/c/663c3da86e807c6c07ed48f911c7526fad6fe1ff
• https://git.kernel.org/stable/c/7f3d5880800f962c347777c4f8358f29f5fc403c
• https://git.kernel.org/stable/c/95bed65cc0eb2a610550abf849a8b94374da80a7
• https://git.kernel.org/stable/c/966d6494e2ed9be9052fcd9815afba830896aaf8
• https://git.kernel.org/stable/c/b7f0ee992adf601aa00c252418266177eb7ac2bc
• https://git.kernel.org/stable/c/f41f097f68a33d392579885426d0734a81219501
• https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html