CVE-2025-38682

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

i2c: core: Fix double-free of fwnode in i2cunregisterdevice()

Before commit df6d7277e552 ("i2c: core: Do not dereference fwnode in struct device"), i2cunregisterdevice() only called fwnodehandleput() on ofnode-s in the form of calling ofnodeput(client->dev.ofnode).

But after this commit the i2cclient's fwnode now unconditionally gets fwnodehandle_put() on it.

When the i2cclient has no primary (ACPI / OF) fwnode but it does have a software fwnode, the software-node will be the primary node and fwnodehandle_put() will put() it.

But for the software fwnode deviceremovesoftware_node() will also put() it leading to a double free:

[ 82.665598] ------------[ cut here ]------------ [ 82.665609] refcountt: underflow; use-after-free. [ 82.665808] WARNING: CPU: 3 PID: 1502 at lib/refcount.c:28 refcountwarnsaturate+0xba/0x11 ... [ 82.666830] RIP: 0010:refcountwarnsaturate+0xba/0x110 ... [ 82.666962] <TASK> [ 82.666971] i2cunregister_device+0x60/0x90

Fix this by not calling fwnodehandleput() when the primary fwnode is a software-node.