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, 106 insertions, 0 deletions

diff --git a/crypto/xxhash_generic.c b/crypto/xxhash_generic.c
new file mode 100644
index 000000000..175bb7ae0
--- /dev/null
+++ b/crypto/xxhash_generic.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/xxhash.h>
+#include <linux/unaligned.h>
+
+#define XXHASH64_BLOCK_SIZE	32
+#define XXHASH64_DIGEST_SIZE	8
+
+struct xxhash64_tfm_ctx {
+	u64 seed;
+};
+
+struct xxhash64_desc_ctx {
+	struct xxh64_state xxhstate;
+};
+
+static int xxhash64_setkey(struct crypto_shash *tfm, const u8 *key,
+			 unsigned int keylen)
+{
+	struct xxhash64_tfm_ctx *tctx = crypto_shash_ctx(tfm);
+
+	if (keylen != sizeof(tctx->seed))
+		return -EINVAL;
+	tctx->seed = get_unaligned_le64(key);
+	return 0;
+}
+
+static int xxhash64_init(struct shash_desc *desc)
+{
+	struct xxhash64_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+	struct xxhash64_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	xxh64_reset(&dctx->xxhstate, tctx->seed);
+
+	return 0;
+}
+
+static int xxhash64_update(struct shash_desc *desc, const u8 *data,
+			 unsigned int length)
+{
+	struct xxhash64_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	xxh64_update(&dctx->xxhstate, data, length);
+
+	return 0;
+}
+
+static int xxhash64_final(struct shash_desc *desc, u8 *out)
+{
+	struct xxhash64_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	put_unaligned_le64(xxh64_digest(&dctx->xxhstate), out);
+
+	return 0;
+}
+
+static int xxhash64_digest(struct shash_desc *desc, const u8 *data,
+			 unsigned int length, u8 *out)
+{
+	struct xxhash64_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+
+	put_unaligned_le64(xxh64(data, length, tctx->seed), out);
+
+	return 0;
+}
+
+static struct shash_alg alg = {
+	.digestsize	= XXHASH64_DIGEST_SIZE,
+	.setkey		= xxhash64_setkey,
+	.init		= xxhash64_init,
+	.update		= xxhash64_update,
+	.final		= xxhash64_final,
+	.digest		= xxhash64_digest,
+	.descsize	= sizeof(struct xxhash64_desc_ctx),
+	.base		= {
+		.cra_name	 = "xxhash64",
+		.cra_driver_name = "xxhash64-generic",
+		.cra_priority	 = 100,
+		.cra_flags	 = CRYPTO_ALG_OPTIONAL_KEY,
+		.cra_blocksize	 = XXHASH64_BLOCK_SIZE,
+		.cra_ctxsize	 = sizeof(struct xxhash64_tfm_ctx),
+		.cra_module	 = THIS_MODULE,
+	}
+};
+
+static int __init xxhash_mod_init(void)
+{
+	return crypto_register_shash(&alg);
+}
+
+static void __exit xxhash_mod_fini(void)
+{
+	crypto_unregister_shash(&alg);
+}
+
+module_init(xxhash_mod_init);
+module_exit(xxhash_mod_fini);
+
+MODULE_AUTHOR("Nikolay Borisov <nborisov@suse.com>");
+MODULE_DESCRIPTION("xxhash calculations wrapper for lib/xxhash.c");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_CRYPTO("xxhash64");
+MODULE_ALIAS_CRYPTO("xxhash64-generic");