Affected: Linux

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

x86/amd_node: Fix PCI device reference counting in amd_smn_init()

The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL.