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, 93 insertions, 0 deletions

diff --git a/tools/include/nolibc/compiler.h b/tools/include/nolibc/compiler.h
new file mode 100644
index 000000000..f2d7a81d0
--- /dev/null
+++ b/tools/include/nolibc/compiler.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * NOLIBC compiler support header
+ * Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
+ */
+#ifndef _NOLIBC_COMPILER_H
+#define _NOLIBC_COMPILER_H
+
+#if defined(__has_attribute)
+#  define __nolibc_has_attribute(attr) __has_attribute(attr)
+#else
+#  define __nolibc_has_attribute(attr) 0
+#endif
+
+#if defined(__has_feature)
+#  define __nolibc_has_feature(feature) __has_feature(feature)
+#else
+#  define __nolibc_has_feature(feature) 0
+#endif
+
+#define __nolibc_aligned(alignment) __attribute__((aligned(alignment)))
+#define __nolibc_aligned_as(type) __nolibc_aligned(__alignof__(type))
+
+#if __nolibc_has_attribute(naked)
+#  define __nolibc_entrypoint __attribute__((naked))
+#  define __nolibc_entrypoint_epilogue()
+#else
+#  define __nolibc_entrypoint __attribute__((optimize("Os", "omit-frame-pointer")))
+#  define __nolibc_entrypoint_epilogue() __builtin_unreachable()
+#endif /* __nolibc_has_attribute(naked) */
+
+#if defined(__SSP__) || defined(__SSP_STRONG__) || defined(__SSP_ALL__) || defined(__SSP_EXPLICIT__)
+
+#define _NOLIBC_STACKPROTECTOR
+
+#endif /* defined(__SSP__) ... */
+
+#if __nolibc_has_attribute(no_stack_protector)
+#  define __nolibc_no_stack_protector __attribute__((no_stack_protector))
+#else
+#  define __nolibc_no_stack_protector __attribute__((__optimize__("-fno-stack-protector")))
+#endif /* __nolibc_has_attribute(no_stack_protector) */
+
+#if __nolibc_has_attribute(__fallthrough__)
+#  define __nolibc_fallthrough do { } while (0); __attribute__((__fallthrough__))
+#else
+#  define __nolibc_fallthrough do { } while (0)
+#endif /* __nolibc_has_attribute(fallthrough) */
+
+#if defined(__STDC_VERSION__)
+#  define __nolibc_stdc_version __STDC_VERSION__
+#else
+#  define __nolibc_stdc_version 0
+#endif
+
+#define __nolibc_version(_major, _minor, _patch) ((_major) * 10000 + (_minor) * 100 + (_patch))
+
+#ifdef __GNUC__
+#  define __nolibc_gnuc_version \
+		__nolibc_version(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
+#else
+#  define __nolibc_gnuc_version 0
+#endif /* __GNUC__ */
+
+#ifdef __clang__
+#  define __nolibc_clang_version \
+		__nolibc_version(__clang_major__, __clang_minor__, __clang_patchlevel__)
+#else
+#  define __nolibc_clang_version 0
+#endif /* __clang__ */
+
+#if __nolibc_stdc_version >= 201112L || \
+	__nolibc_gnuc_version >= __nolibc_version(4, 6, 0) || \
+	__nolibc_clang_version >= __nolibc_version(3, 0, 0)
+#  define __nolibc_static_assert(_t) _Static_assert(_t, "")
+#else
+#  define __nolibc_static_assert(_t)
+#endif
+
+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define _NOLIBC_OPTIMIZER_HIDE_VAR(var)	__asm__ ("" : "+r" (var))
+
+#if __nolibc_has_feature(undefined_behavior_sanitizer)
+#  if defined(__clang__)
+#    define __nolibc_no_sanitize_undefined __attribute__((no_sanitize("function")))
+#  else
+#    define __nolibc_no_sanitize_undefined __attribute__((no_sanitize_undefined))
+#  endif
+#else
+#  define __nolibc_no_sanitize_undefined
+#endif
+
+#endif /* _NOLIBC_COMPILER_H */