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, 77 insertions, 0 deletions

diff --git a/include/crypto/aes-cbc.h b/include/crypto/aes-cbc.h
new file mode 100644
index 000000000..7bae34093
--- /dev/null
+++ b/include/crypto/aes-cbc.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * AES-CBC and AES-CBC-CTS unauthenticated encryption and decryption
+ *
+ * Copyright 2026 Google LLC
+ */
+#ifndef _CRYPTO_AES_CBC_H
+#define _CRYPTO_AES_CBC_H
+
+#include <crypto/aes.h>
+
+/**
+ * aes_cbc_encrypt() - Encrypt data using AES-CBC
+ * @dst: The destination buffer.  Can be in-place or out-of-place.  For other
+ *	 overlaps the behavior is unspecified.
+ * @src: The source data
+ * @len: Number of bytes to encrypt.  Must be a multiple of AES_BLOCK_SIZE.
+ * @iv: The initialization vector.  It is updated with the next value, i.e. the
+ *	last ciphertext block (or left unchanged if @len == 0).
+ * @key: The key, already prepared using aes_preparekey() or aes_prepareenckey()
+ *
+ * This supports incremental encryption.  The length of each chunk must be a
+ * multiple of AES_BLOCK_SIZE, and the updated @iv must be passed in each time.
+ *
+ * Context: Any context.
+ */
+void aes_cbc_encrypt(u8 *dst, const u8 *src, size_t len,
+		     u8 iv[at_least AES_BLOCK_SIZE], aes_encrypt_arg key);
+
+/**
+ * aes_cbc_decrypt() - Decrypt data using AES-CBC
+ * @dst: The destination buffer.  Can be in-place or out-of-place.  For other
+ *	 overlaps the behavior is unspecified.
+ * @src: The source data
+ * @len: Number of bytes to decrypt.  Must be a multiple of AES_BLOCK_SIZE.
+ * @iv: The initialization vector.  It is updated with the next value, i.e. the
+ *	last ciphertext block (or left unchanged if @len == 0).
+ * @key: The key, already prepared using aes_preparekey()
+ *
+ * This supports incremental decryption.  The length of each chunk must be a
+ * multiple of AES_BLOCK_SIZE, and the updated @iv must be passed in each time.
+ *
+ * Context: Any context.
+ */
+void aes_cbc_decrypt(u8 *dst, const u8 *src, size_t len,
+		     u8 iv[at_least AES_BLOCK_SIZE], const struct aes_key *key);
+
+/**
+ * aes_cbc_cts_encrypt() - Encrypt data using AES-CBC-CTS (CS3 variant)
+ * @dst: The destination buffer.  Can be in-place or out-of-place.  For other
+ *	 overlaps the behavior is unspecified.
+ * @src: The source data
+ * @len: Number of bytes to encrypt, at least AES_BLOCK_SIZE
+ * @iv: The initialization vector, clobbered by this function
+ * @key: The key, already prepared using aes_preparekey() or aes_prepareenckey()
+ *
+ * Context: Any context.
+ */
+void aes_cbc_cts_encrypt(u8 *dst, const u8 *src, size_t len,
+			 u8 iv[at_least AES_BLOCK_SIZE], aes_encrypt_arg key);
+
+/**
+ * aes_cbc_cts_decrypt() - Decrypt data using AES-CBC-CTS (CS3 variant)
+ * @dst: The destination buffer.  Can be in-place or out-of-place.  For other
+ *	 overlaps the behavior is unspecified.
+ * @src: The source data
+ * @len: Number of bytes to decrypt, at least AES_BLOCK_SIZE
+ * @iv: The initialization vector, clobbered by this function
+ * @key: The key, already prepared using aes_preparekey()
+ *
+ * Context: Any context.
+ */
+void aes_cbc_cts_decrypt(u8 *dst, const u8 *src, size_t len,
+			 u8 iv[at_least AES_BLOCK_SIZE],
+			 const struct aes_key *key);
+
+#endif /* _CRYPTO_AES_CBC_H */