CVE-2025-37905

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

firmware: arm_scmi: Balance device refcount when destroying devices

Using device_find_child() to lookup the proper SCMI device to destroy causes an unbalance in device refcount, since device_find_child() calls an implicit get_device(): this, in turns, inhibits the call of the provided release methods upon devices destruction.

As a consequence, one of the structures that is not freed properly upon destruction is the internal struct device_private dev->p populated by the drivers subsystem core.

KMemleak detects this situation since loading/unloding some SCMI driver causes related devices to be created/destroyed without calling any device_release method.

unreferenced object 0xffff00000f583800 (size 512): comm insmod, pid 227, jiffies 4294912190 hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 …..N………. ff ff ff ff ff ff ff ff 60 36 1d 8a 00 80 ff ff ……..`6…… backtrace (crc 114e2eed): kmemleak_alloc+0xbc/0xd8 __kmalloc_cache_noprof+0x2dc/0x398 device_add+0x954/0x12d0 device_register+0x28/0x40 __scmi_device_create.part.0+0x1bc/0x380 scmi_device_create+0x2d0/0x390 scmi_create_protocol_devices+0x74/0xf8 scmi_device_request_notifier+0x1f8/0x2a8 notifier_call_chain+0x110/0x3b0 blocking_notifier_call_chain+0x70/0xb0 scmi_driver_register+0x350/0x7f0 0xffff80000a3b3038 do_one_initcall+0x12c/0x730 do_init_module+0x1dc/0x640 load_module+0x4b20/0x5b70 init_module_from_file+0xec/0x158

$ ./scripts/faddr2line ./vmlinux device_add+0x954/0x12d0 device_add+0x954/0x12d0: kmalloc_noprof at include/linux/slab.h:901 (inlined by) kzalloc_noprof at include/linux/slab.h:1037 (inlined by) device_private_init at drivers/base/core.c:3510 (inlined by) device_add at drivers/base/core.c:3561

Balance device refcount by issuing a put_device() on devices found via device_find_child().

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/2fbf6c9695ad9f05e7e5c166bf43fac7cb3276b3
• https://git.kernel.org/stable/c/8a8a3547d5c4960da053df49c75bf623827a25da
• https://git.kernel.org/stable/c/91ff1e9652fb9beb0174267d6bb38243dff211bb
• https://git.kernel.org/stable/c/969d8beaa2e374387bf9aa5602ef84fc50bb48d8
• https://git.kernel.org/stable/c/9ca67840c0ddf3f39407339624cef824a4f27599
• https://git.kernel.org/stable/c/ff4273d47da81b95ed9396110bcbd1b7b7470fe8
• https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html