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

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.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 78 insertions, 0 deletions

diff --git a/drivers/net/wireguard/main.c b/drivers/net/wireguard/main.c
new file mode 100644
index 000000000..a00671b58
--- /dev/null
+++ b/drivers/net/wireguard/main.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "version.h"
+#include "device.h"
+#include "noise.h"
+#include "queueing.h"
+#include "ratelimiter.h"
+#include "netlink.h"
+
+#include <uapi/linux/wireguard.h>
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <net/genetlink.h>
+#include <net/rtnetlink.h>
+
+static int __init wg_mod_init(void)
+{
+	int ret;
+
+	ret = wg_allowedips_slab_init();
+	if (ret < 0)
+		goto err_allowedips;
+
+#ifdef DEBUG
+	ret = -ENOTRECOVERABLE;
+	if (!wg_allowedips_selftest() || !wg_packet_counter_selftest() ||
+	    !wg_ratelimiter_selftest())
+		goto err_peer;
+#endif
+	wg_noise_init();
+
+	ret = wg_peer_init();
+	if (ret < 0)
+		goto err_peer;
+
+	ret = wg_device_init();
+	if (ret < 0)
+		goto err_device;
+
+	ret = wg_genetlink_init();
+	if (ret < 0)
+		goto err_netlink;
+
+	pr_info("WireGuard " WIREGUARD_VERSION " loaded. See www.wireguard.com for information.\n");
+	pr_info("Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.\n");
+
+	return 0;
+
+err_netlink:
+	wg_device_uninit();
+err_device:
+	wg_peer_uninit();
+err_peer:
+	wg_allowedips_slab_uninit();
+err_allowedips:
+	return ret;
+}
+
+static void __exit wg_mod_exit(void)
+{
+	wg_genetlink_uninit();
+	wg_device_uninit();
+	wg_peer_uninit();
+	wg_allowedips_slab_uninit();
+}
+
+module_init(wg_mod_init);
+module_exit(wg_mod_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("WireGuard secure network tunnel");
+MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
+MODULE_VERSION(WIREGUARD_VERSION);
+MODULE_ALIAS_RTNL_LINK(KBUILD_MODNAME);
+MODULE_ALIAS_GENL_FAMILY(WG_GENL_NAME);