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, 67 insertions, 0 deletions

diff --git a/include/crypto/poly1305.h b/include/crypto/poly1305.h
new file mode 100644
index 000000000..190beb427
--- /dev/null
+++ b/include/crypto/poly1305.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common values for the Poly1305 algorithm
+ */
+
+#ifndef _CRYPTO_POLY1305_H
+#define _CRYPTO_POLY1305_H
+
+#include <linux/types.h>
+
+#define POLY1305_BLOCK_SIZE	16
+#define POLY1305_KEY_SIZE	32
+#define POLY1305_DIGEST_SIZE	16
+
+/* The poly1305_key and poly1305_state types are mostly opaque and
+ * implementation-defined. Limbs might be in base 2^64 or base 2^26, or
+ * different yet. The union type provided keeps these 64-bit aligned for the
+ * case in which this is implemented using 64x64 multiplies.
+ */
+
+struct poly1305_key {
+	union {
+		u32 r[5];
+		u64 r64[3];
+	};
+};
+
+struct poly1305_core_key {
+	struct poly1305_key key;
+	struct poly1305_key precomputed_s;
+};
+
+struct poly1305_state {
+	union {
+		u32 h[5];
+		u64 h64[3];
+	};
+};
+
+/* Combined state for block function. */
+struct poly1305_block_state {
+	/* accumulator */
+	struct poly1305_state h;
+	/* key */
+	union {
+		struct poly1305_key opaque_r[CONFIG_CRYPTO_LIB_POLY1305_RSIZE];
+		struct poly1305_core_key core_r;
+	};
+};
+
+struct poly1305_desc_ctx {
+	/* partial buffer */
+	u8 buf[POLY1305_BLOCK_SIZE];
+	/* bytes used in partial buffer */
+	unsigned int buflen;
+	/* finalize key */
+	u32 s[4];
+	struct poly1305_block_state state;
+};
+
+void poly1305_init(struct poly1305_desc_ctx *desc,
+		   const u8 key[at_least POLY1305_KEY_SIZE]);
+void poly1305_update(struct poly1305_desc_ctx *desc,
+		     const u8 *src, unsigned int nbytes);
+void poly1305_final(struct poly1305_desc_ctx *desc, u8 *digest);
+
+#endif