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, 64 insertions, 0 deletions

diff --git a/include/asm-generic/bitops/le.h b/include/asm-generic/bitops/le.h
new file mode 100644
index 000000000..e3b0da9a2
--- /dev/null
+++ b/include/asm-generic/bitops/le.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_BITOPS_LE_H_
+#define _ASM_GENERIC_BITOPS_LE_H_
+
+#include <asm/types.h>
+#include <asm/byteorder.h>
+
+#if defined(__LITTLE_ENDIAN)
+
+#define BITOP_LE_SWIZZLE	0
+
+#elif defined(__BIG_ENDIAN)
+
+#define BITOP_LE_SWIZZLE	((BITS_PER_LONG-1) & ~0x7)
+
+#endif
+
+
+static inline int test_bit_le(unsigned long nr, const void *addr)
+{
+	return test_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void set_bit_le(unsigned long nr, void *addr)
+{
+	set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void clear_bit_le(unsigned long nr, void *addr)
+{
+	clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void __set_bit_le(unsigned long nr, void *addr)
+{
+	__set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void __clear_bit_le(unsigned long nr, void *addr)
+{
+	__clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int test_and_set_bit_le(unsigned long nr, void *addr)
+{
+	return test_and_set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int test_and_clear_bit_le(unsigned long nr, void *addr)
+{
+	return test_and_clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int __test_and_set_bit_le(unsigned long nr, void *addr)
+{
+	return __test_and_set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int __test_and_clear_bit_le(unsigned long nr, void *addr)
+{
+	return __test_and_clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+#endif /* _ASM_GENERIC_BITOPS_LE_H_ */