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, 100 insertions, 0 deletions

diff --git a/lib/crypto/poly1305.c b/lib/crypto/poly1305.c
new file mode 100644
index 000000000..f313ccc4b
--- /dev/null
+++ b/lib/crypto/poly1305.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Poly1305 authenticator algorithm, RFC7539
+ *
+ * Copyright (C) 2015 Martin Willi
+ *
+ * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
+ */
+
+#include <crypto/internal/poly1305.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/unaligned.h>
+
+#ifdef CONFIG_CRYPTO_LIB_POLY1305_ARCH
+#include "poly1305.h" /* $(SRCARCH)/poly1305.h */
+#else
+#define poly1305_block_init	poly1305_block_init_generic
+#define poly1305_blocks		poly1305_blocks_generic
+#define poly1305_emit		poly1305_emit_generic
+#endif
+
+void poly1305_init(struct poly1305_desc_ctx *desc,
+		   const u8 key[POLY1305_KEY_SIZE])
+{
+	desc->s[0] = get_unaligned_le32(key + 16);
+	desc->s[1] = get_unaligned_le32(key + 20);
+	desc->s[2] = get_unaligned_le32(key + 24);
+	desc->s[3] = get_unaligned_le32(key + 28);
+	desc->buflen = 0;
+	poly1305_block_init(&desc->state, key);
+}
+EXPORT_SYMBOL(poly1305_init);
+
+void poly1305_update(struct poly1305_desc_ctx *desc,
+		     const u8 *src, unsigned int nbytes)
+{
+	if (desc->buflen + nbytes >= POLY1305_BLOCK_SIZE) {
+		unsigned int bulk_len;
+
+		if (desc->buflen) {
+			unsigned int l = POLY1305_BLOCK_SIZE - desc->buflen;
+
+			memcpy(&desc->buf[desc->buflen], src, l);
+			src += l;
+			nbytes -= l;
+
+			poly1305_blocks(&desc->state, desc->buf,
+					POLY1305_BLOCK_SIZE, 1);
+			desc->buflen = 0;
+		}
+
+		bulk_len = round_down(nbytes, POLY1305_BLOCK_SIZE);
+		nbytes %= POLY1305_BLOCK_SIZE;
+
+		if (bulk_len) {
+			poly1305_blocks(&desc->state, src, bulk_len, 1);
+			src += bulk_len;
+		}
+	}
+	if (nbytes) {
+		memcpy(&desc->buf[desc->buflen], src, nbytes);
+		desc->buflen += nbytes;
+	}
+}
+EXPORT_SYMBOL(poly1305_update);
+
+void poly1305_final(struct poly1305_desc_ctx *desc, u8 *dst)
+{
+	if (unlikely(desc->buflen)) {
+		desc->buf[desc->buflen++] = 1;
+		memset(desc->buf + desc->buflen, 0,
+		       POLY1305_BLOCK_SIZE - desc->buflen);
+		poly1305_blocks(&desc->state, desc->buf, POLY1305_BLOCK_SIZE,
+				0);
+	}
+
+	poly1305_emit(&desc->state.h, dst, desc->s);
+	*desc = (struct poly1305_desc_ctx){};
+}
+EXPORT_SYMBOL(poly1305_final);
+
+#ifdef poly1305_mod_init_arch
+static int __init poly1305_mod_init(void)
+{
+	poly1305_mod_init_arch();
+	return 0;
+}
+subsys_initcall(poly1305_mod_init);
+
+static void __exit poly1305_mod_exit(void)
+{
+}
+module_exit(poly1305_mod_exit);
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Poly1305 authenticator algorithm, RFC7539");