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, 97 insertions, 0 deletions

diff --git a/include/crypto/internal/sig.h b/include/crypto/internal/sig.h
new file mode 100644
index 000000000..b16648c1a
--- /dev/null
+++ b/include/crypto/internal/sig.h
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Public Key Signature Algorithm
+ *
+ * Copyright (c) 2023 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+#ifndef _CRYPTO_INTERNAL_SIG_H
+#define _CRYPTO_INTERNAL_SIG_H
+
+#include <crypto/algapi.h>
+#include <crypto/sig.h>
+
+struct sig_instance {
+	void (*free)(struct sig_instance *inst);
+	union {
+		struct {
+			char head[offsetof(struct sig_alg, base)];
+			struct crypto_instance base;
+		};
+		struct sig_alg alg;
+	};
+};
+
+struct crypto_sig_spawn {
+	struct crypto_spawn base;
+};
+
+static inline void *crypto_sig_ctx(struct crypto_sig *tfm)
+{
+	return crypto_tfm_ctx(&tfm->base);
+}
+
+/**
+ * crypto_register_sig() -- Register public key signature algorithm
+ *
+ * Function registers an implementation of a public key signature algorithm
+ *
+ * @alg:	algorithm definition
+ *
+ * Return: zero on success; error code in case of error
+ */
+int crypto_register_sig(struct sig_alg *alg);
+
+/**
+ * crypto_unregister_sig() -- Unregister public key signature algorithm
+ *
+ * Function unregisters an implementation of a public key signature algorithm
+ *
+ * @alg:	algorithm definition
+ */
+void crypto_unregister_sig(struct sig_alg *alg);
+
+int sig_register_instance(struct crypto_template *tmpl,
+			  struct sig_instance *inst);
+
+static inline struct sig_instance *sig_instance(struct crypto_instance *inst)
+{
+	return container_of(&inst->alg, struct sig_instance, alg.base);
+}
+
+static inline struct sig_instance *sig_alg_instance(struct crypto_sig *tfm)
+{
+	return sig_instance(crypto_tfm_alg_instance(&tfm->base));
+}
+
+static inline struct crypto_instance *sig_crypto_instance(struct sig_instance
+									*inst)
+{
+	return container_of(&inst->alg.base, struct crypto_instance, alg);
+}
+
+static inline void *sig_instance_ctx(struct sig_instance *inst)
+{
+	return crypto_instance_ctx(sig_crypto_instance(inst));
+}
+
+int crypto_grab_sig(struct crypto_sig_spawn *spawn,
+		    struct crypto_instance *inst,
+		    const char *name, u32 type, u32 mask);
+
+static inline struct crypto_sig *crypto_spawn_sig(struct crypto_sig_spawn
+								   *spawn)
+{
+	return crypto_spawn_tfm2(&spawn->base);
+}
+
+static inline void crypto_drop_sig(struct crypto_sig_spawn *spawn)
+{
+	crypto_drop_spawn(&spawn->base);
+}
+
+static inline struct sig_alg *crypto_spawn_sig_alg(struct crypto_sig_spawn
+								    *spawn)
+{
+	return container_of(spawn->base.alg, struct sig_alg, base);
+}
+#endif