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, 281 insertions, 0 deletions

diff --git a/rust/zerocopy/src/deprecated.rs b/rust/zerocopy/src/deprecated.rs
new file mode 100644
index 000000000..59ddd35c7
--- /dev/null
+++ b/rust/zerocopy/src/deprecated.rs
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+//
+// Copyright 2024 The Fuchsia Authors
+//
+// Licensed under the 2-Clause BSD License <LICENSE-BSD or
+// https://opensource.org/license/bsd-2-clause>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+//! Deprecated items. These are kept separate so that they don't clutter up
+//! other modules.
+
+use super::*;
+
+impl<B, T> Ref<B, T>
+where
+    B: ByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_bytes`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new(bytes: B) -> Option<Ref<B, T>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_prefix`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_from_prefix(bytes: B) -> Option<(Ref<B, T>, B)> {
+        Self::from_prefix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_suffix`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_from_suffix(bytes: B) -> Option<(B, Ref<B, T>)> {
+        Self::from_suffix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: ByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_bytes`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned(bytes: B) -> Option<Ref<B, T>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_prefix`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned_from_prefix(bytes: B) -> Option<(Ref<B, T>, B)> {
+        Self::from_prefix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_suffix`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned_from_suffix(bytes: B) -> Option<(B, Ref<B, T>)> {
+        Self::from_suffix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: ByteSlice,
+    T: Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::from_bytes` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice(bytes: B) -> Option<Ref<B, [T]>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: ByteSlice,
+    T: Unaligned + Immutable,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "`Ref::from_bytes` now supports slices; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_unaligned(bytes: B) -> Option<Ref<B, [T]>> {
+        Ref::from_bytes(bytes).ok()
+    }
+}
+
+impl<'a, B, T> Ref<B, [T]>
+where
+    B: 'a + IntoByteSlice<'a>,
+    T: FromBytes + Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::into_ref` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn into_slice(self) -> &'a [T] {
+        Ref::into_ref(self)
+    }
+}
+
+impl<'a, B, T> Ref<B, [T]>
+where
+    B: 'a + IntoByteSliceMut<'a>,
+    T: FromBytes + IntoBytes + Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::into_mut` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn into_mut_slice(self) -> &'a mut [T] {
+        Ref::into_mut(self)
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: SplitByteSlice,
+    T: Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "replaced by `Ref::from_prefix_with_elems`")]
+    #[must_use = "has no side effects"]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_from_prefix(bytes: B, count: usize) -> Option<(Ref<B, [T]>, B)> {
+        Ref::from_prefix_with_elems(bytes, count).ok()
+    }
+
+    #[deprecated(since = "0.8.0", note = "replaced by `Ref::from_suffix_with_elems`")]
+    #[must_use = "has no side effects"]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_from_suffix(bytes: B, count: usize) -> Option<(B, Ref<B, [T]>)> {
+        Ref::from_suffix_with_elems(bytes, count).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: SplitByteSlice,
+    T: Unaligned + Immutable,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_prefix_with_elems`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_slice_unaligned_from_prefix(bytes: B, count: usize) -> Option<(Ref<B, [T]>, B)> {
+        Ref::from_prefix_with_elems(bytes, count).ok()
+    }
+
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_suffix_with_elems`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_slice_unaligned_from_suffix(bytes: B, count: usize) -> Option<(B, Ref<B, [T]>)> {
+        Ref::from_suffix_with_elems(bytes, count).ok()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_ref_methods() {
+        let bytes = &[0u8; 1][..];
+        let bytes_slice = &[0u8; 4][..];
+
+        let r: Option<Ref<&[u8], u8>> = Ref::new(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], u8>, &[u8])> = Ref::new_from_prefix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], u8>)> = Ref::new_from_suffix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], u8>> = Ref::new_unaligned(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], u8>, &[u8])> = Ref::new_unaligned_from_prefix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], u8>)> = Ref::new_unaligned_from_suffix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], [u8]>> = Ref::new_slice(bytes_slice);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], [u8]>> = Ref::new_slice_unaligned(bytes_slice);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], [u8]>, &[u8])> = Ref::new_slice_from_prefix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], [u8]>)> = Ref::new_slice_from_suffix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], [u8]>, &[u8])> =
+            Ref::new_slice_unaligned_from_prefix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], [u8]>)> =
+            Ref::new_slice_unaligned_from_suffix(bytes_slice, 1);
+        assert!(r.is_some());
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_into_slice() {
+        let bytes = &[0u8; 4][..];
+        let r: Ref<&[u8], [u8]> = Ref::from_bytes(bytes).unwrap();
+        let slice: &[u8] = r.into_slice();
+        assert_eq!(slice.len(), 4);
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_into_mut_slice() {
+        let mut bytes = [0u8; 4];
+        let r: Ref<&mut [u8], [u8]> = Ref::from_bytes(&mut bytes[..]).unwrap();
+        let slice: &mut [u8] = r.into_mut_slice();
+        assert_eq!(slice.len(), 4);
+    }
+}