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, 53 insertions, 0 deletions

diff --git a/net/ceph/crypto.h b/net/ceph/crypto.h
new file mode 100644
index 000000000..3a2ade15a
--- /dev/null
+++ b/net/ceph/crypto.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _FS_CEPH_CRYPTO_H
+#define _FS_CEPH_CRYPTO_H
+
+#include <crypto/sha2.h>
+#include <linux/ceph/types.h>
+#include <linux/ceph/buffer.h>
+
+#define CEPH_MAX_KEY_LEN		32
+#define CEPH_MAX_CON_SECRET_LEN		64
+
+/*
+ * cryptographic secret
+ */
+struct ceph_crypto_key {
+	int type;
+	struct ceph_timespec created;
+	int len;
+	void *key;
+
+	union {
+		struct crypto_sync_skcipher *aes_tfm;
+		struct {
+			struct hmac_sha256_key hmac_key;
+			const struct krb5_enctype *krb5_type;
+			struct crypto_aead *krb5_tfms[3];
+		};
+	};
+};
+
+int ceph_crypto_key_prepare(struct ceph_crypto_key *key,
+			    const u32 *key_usages, int key_usage_cnt);
+int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
+			  const struct ceph_crypto_key *src);
+int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end);
+int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *in);
+void ceph_crypto_key_destroy(struct ceph_crypto_key *key);
+
+/* crypto.c */
+int ceph_crypt(const struct ceph_crypto_key *key, int usage_slot, bool encrypt,
+	       void *buf, int buf_len, int in_len, int *pout_len);
+int ceph_crypt_data_offset(const struct ceph_crypto_key *key);
+int ceph_crypt_buflen(const struct ceph_crypto_key *key, int data_len);
+void ceph_hmac_sha256(const struct ceph_crypto_key *key, const void *buf,
+		      int buf_len, u8 hmac[SHA256_DIGEST_SIZE]);
+int ceph_crypto_init(void);
+void ceph_crypto_shutdown(void);
+
+/* armor.c */
+int ceph_armor(char *dst, const char *src, const char *end);
+int ceph_unarmor(char *dst, const char *src, const char *end);
+
+#endif