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, 56 insertions, 0 deletions

diff --git a/include/crypto/internal/poly1305.h b/include/crypto/internal/poly1305.h
new file mode 100644
index 000000000..a72fff409
--- /dev/null
+++ b/include/crypto/internal/poly1305.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common values for the Poly1305 algorithm
+ */
+
+#ifndef _CRYPTO_INTERNAL_POLY1305_H
+#define _CRYPTO_INTERNAL_POLY1305_H
+
+#include <crypto/poly1305.h>
+#include <linux/types.h>
+
+/*
+ * Poly1305 core functions.  These only accept whole blocks; the caller must
+ * handle any needed block buffering and padding.  'hibit' must be 1 for any
+ * full blocks, or 0 for the final block if it had to be padded.  If 'nonce' is
+ * non-NULL, then it's added at the end to compute the Poly1305 MAC.  Otherwise,
+ * only the ε-almost-∆-universal hash function (not the full MAC) is computed.
+ */
+
+void poly1305_core_setkey(struct poly1305_core_key *key,
+			  const u8 raw_key[POLY1305_BLOCK_SIZE]);
+static inline void poly1305_core_init(struct poly1305_state *state)
+{
+	*state = (struct poly1305_state){};
+}
+
+void poly1305_core_blocks(struct poly1305_state *state,
+			  const struct poly1305_core_key *key, const void *src,
+			  unsigned int nblocks, u32 hibit);
+void poly1305_core_emit(const struct poly1305_state *state, const u32 nonce[4],
+			void *dst);
+
+static inline void
+poly1305_block_init_generic(struct poly1305_block_state *desc,
+			    const u8 raw_key[POLY1305_BLOCK_SIZE])
+{
+	poly1305_core_init(&desc->h);
+	poly1305_core_setkey(&desc->core_r, raw_key);
+}
+
+static inline void poly1305_blocks_generic(struct poly1305_block_state *state,
+					   const u8 *src, unsigned int len,
+					   u32 padbit)
+{
+	poly1305_core_blocks(&state->h, &state->core_r, src,
+			     len / POLY1305_BLOCK_SIZE, padbit);
+}
+
+static inline void poly1305_emit_generic(const struct poly1305_state *state,
+					 u8 digest[POLY1305_DIGEST_SIZE],
+					 const u32 nonce[4])
+{
+	poly1305_core_emit(state, nonce, digest);
+}
+
+#endif