CVE-2025-37905

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

firmware: arm_scmi: Balance device refcount when destroying devices

Using devicefindchild() to lookup the proper SCMI device to destroy causes an unbalance in device refcount, since devicefindchild() 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 __kmalloccachenoprof+0x2dc/0x398 deviceadd+0x954/0x12d0 deviceregister+0x28/0x40 _scmidevicecreate.part.0+0x1bc/0x380 scmidevicecreate+0x2d0/0x390 scmicreateprotocoldevices+0x74/0xf8 scmidevicerequestnotifier+0x1f8/0x2a8 notifiercallchain+0x110/0x3b0 blockingnotifiercallchain+0x70/0xb0 scmidriverregister+0x350/0x7f0 0xffff80000a3b3038 dooneinitcall+0x12c/0x730 doinitmodule+0x1dc/0x640 loadmodule+0x4b20/0x5b70 initmodulefromfile+0xec/0x158

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

Balance device refcount by issuing a putdevice() on devices found via devicefind_child().