firmware_loader: use SHA-256 library API instead of crypto_shash API

This user of SHA-256 does not support any other algorithm, so the
crypto_shash abstraction provides no value.  Just use the SHA-256
library API instead, which is much simpler and easier to use.

Also take advantage of printk's built-in hex conversion using %*phN.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250428190909.852705-1-ebiggers@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: ebiggers

drivers/base/firmware_loader/Kconfig

@@ -3,8 +3,7 @@ menu "Firmware loader"
 
 config FW_LOADER
 	tristate "Firmware loading facility" if EXPERT
-	select CRYPTO_HASH if FW_LOADER_DEBUG
-	select CRYPTO_SHA256 if FW_LOADER_DEBUG
+	select CRYPTO_LIB_SHA256 if FW_LOADER_DEBUG
 	default y
 	help
 	  This enables the firmware loading facility in the kernel. The kernel
@@ -28,7 +27,6 @@ config FW_LOADER
 
 config FW_LOADER_DEBUG
 	bool "Log filenames and checksums for loaded firmware"
-	depends on CRYPTO = FW_LOADER || CRYPTO=y
 	depends on DYNAMIC_DEBUG
 	depends on FW_LOADER
 	default FW_LOADER

drivers/base/firmware_loader/main.c

@@ -806,41 +806,15 @@ static void fw_abort_batch_reqs(struct firmware *fw)
 }
 
 #if defined(CONFIG_FW_LOADER_DEBUG)
-#include <crypto/hash.h>
 #include <crypto/sha2.h>
 
 static void fw_log_firmware_info(const struct firmware *fw, const char *name, struct device *device)
 {
-	struct shash_desc *shash;
-	struct crypto_shash *alg;
-	u8 *sha256buf;
-	char *outbuf;
+	u8 digest[SHA256_DIGEST_SIZE];
 
-	alg = crypto_alloc_shash("sha256", 0, 0);
-	if (IS_ERR(alg))
-		return;
-
-	sha256buf = kmalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
-	outbuf = kmalloc(SHA256_BLOCK_SIZE + 1, GFP_KERNEL);
-	shash = kmalloc(sizeof(*shash) + crypto_shash_descsize(alg), GFP_KERNEL);
-	if (!sha256buf || !outbuf || !shash)
-		goto out_free;
-
-	shash->tfm = alg;
-
-	if (crypto_shash_digest(shash, fw->data, fw->size, sha256buf) < 0)
-		goto out_free;
-
-	for (int i = 0; i < SHA256_DIGEST_SIZE; i++)
-		sprintf(&outbuf[i * 2], "%02x", sha256buf[i]);
-	outbuf[SHA256_BLOCK_SIZE] = 0;
-	dev_dbg(device, "Loaded FW: %s, sha256: %s\n", name, outbuf);
-
-out_free:
-	kfree(shash);
-	kfree(outbuf);
-	kfree(sha256buf);
-	crypto_free_shash(alg);
+	sha256(fw->data, fw->size, digest);
+	dev_dbg(device, "Loaded FW: %s, sha256: %*phN\n",
+		name, SHA256_DIGEST_SIZE, digest);
 }
 #else
 static void fw_log_firmware_info(const struct firmware *fw, const char *name,