dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel()grafted

When dma_device_put() drops the last reference on chan->device->ref,
dma_device_release() runs and may free the dma_device along with its
channels.

dma_chan_put() then still reads chan->device->owner via
dma_chan_to_owner() for the trailing module_put(). KASAN catches it:

	slab-use-after-free in dma_chan_put+0x3e6/0x4c0
	Read of size 8 by task insmod/6319
	Freed by task 6319:
	  kfree+0x225/0x470
	  dma_chan_put+0x395/0x4c0
	  dmaengine_put+0xf8/0x160

Cache the module owner in dma_chan_put() before the put so the trailing
module_put() does not need chan->device.

Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct")
Suggested-by: Sashiko <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 111 insertions, 0 deletions

diff --git a/crypto/blake2b.c b/crypto/blake2b.c
new file mode 100644
index 000000000..67a6dae43
--- /dev/null
+++ b/crypto/blake2b.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Crypto API support for BLAKE2b
+ *
+ * Copyright 2025 Google LLC
+ */
+#include <crypto/blake2b.h>
+#include <crypto/internal/hash.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+struct blake2b_tfm_ctx {
+	unsigned int keylen;
+	u8 key[BLAKE2B_KEY_SIZE];
+};
+
+static int crypto_blake2b_setkey(struct crypto_shash *tfm,
+				 const u8 *key, unsigned int keylen)
+{
+	struct blake2b_tfm_ctx *tctx = crypto_shash_ctx(tfm);
+
+	if (keylen > BLAKE2B_KEY_SIZE)
+		return -EINVAL;
+	memcpy(tctx->key, key, keylen);
+	tctx->keylen = keylen;
+	return 0;
+}
+
+#define BLAKE2B_CTX(desc) ((struct blake2b_ctx *)shash_desc_ctx(desc))
+
+static int crypto_blake2b_init(struct shash_desc *desc)
+{
+	const struct blake2b_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+	unsigned int digestsize = crypto_shash_digestsize(desc->tfm);
+
+	blake2b_init_key(BLAKE2B_CTX(desc), digestsize,
+			 tctx->key, tctx->keylen);
+	return 0;
+}
+
+static int crypto_blake2b_update(struct shash_desc *desc,
+				 const u8 *data, unsigned int len)
+{
+	blake2b_update(BLAKE2B_CTX(desc), data, len);
+	return 0;
+}
+
+static int crypto_blake2b_final(struct shash_desc *desc, u8 *out)
+{
+	blake2b_final(BLAKE2B_CTX(desc), out);
+	return 0;
+}
+
+static int crypto_blake2b_digest(struct shash_desc *desc,
+				 const u8 *data, unsigned int len, u8 *out)
+{
+	const struct blake2b_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+	unsigned int digestsize = crypto_shash_digestsize(desc->tfm);
+
+	blake2b(tctx->key, tctx->keylen, data, len, out, digestsize);
+	return 0;
+}
+
+#define BLAKE2B_ALG(name, digest_size)					\
+	{								\
+		.base.cra_name		= name,				\
+		.base.cra_driver_name	= name "-lib",			\
+		.base.cra_priority	= 300,				\
+		.base.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,	\
+		.base.cra_blocksize	= BLAKE2B_BLOCK_SIZE,		\
+		.base.cra_ctxsize	= sizeof(struct blake2b_tfm_ctx), \
+		.base.cra_module	= THIS_MODULE,			\
+		.digestsize		= digest_size,			\
+		.setkey			= crypto_blake2b_setkey,	\
+		.init			= crypto_blake2b_init,		\
+		.update			= crypto_blake2b_update,	\
+		.final			= crypto_blake2b_final,		\
+		.digest			= crypto_blake2b_digest,	\
+		.descsize		= sizeof(struct blake2b_ctx),	\
+	}
+
+static struct shash_alg algs[] = {
+	BLAKE2B_ALG("blake2b-160", BLAKE2B_160_HASH_SIZE),
+	BLAKE2B_ALG("blake2b-256", BLAKE2B_256_HASH_SIZE),
+	BLAKE2B_ALG("blake2b-384", BLAKE2B_384_HASH_SIZE),
+	BLAKE2B_ALG("blake2b-512", BLAKE2B_512_HASH_SIZE),
+};
+
+static int __init crypto_blake2b_mod_init(void)
+{
+	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
+}
+module_init(crypto_blake2b_mod_init);
+
+static void __exit crypto_blake2b_mod_exit(void)
+{
+	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
+}
+module_exit(crypto_blake2b_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Crypto API support for BLAKE2b");
+
+MODULE_ALIAS_CRYPTO("blake2b-160");
+MODULE_ALIAS_CRYPTO("blake2b-160-lib");
+MODULE_ALIAS_CRYPTO("blake2b-256");
+MODULE_ALIAS_CRYPTO("blake2b-256-lib");
+MODULE_ALIAS_CRYPTO("blake2b-384");
+MODULE_ALIAS_CRYPTO("blake2b-384-lib");
+MODULE_ALIAS_CRYPTO("blake2b-512");
+MODULE_ALIAS_CRYPTO("blake2b-512-lib");