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, 94 insertions, 0 deletions

diff --git a/scripts/mksysmap b/scripts/mksysmap
new file mode 100755
index 000000000..c4531eacd
--- /dev/null
+++ b/scripts/mksysmap
@@ -0,0 +1,94 @@
+#!/bin/sed -f
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# sed script to filter out symbols that are not needed for System.map,
+# or not suitable for kallsyms. The input should be 'nm -n <file>'.
+#
+# System.map is used by module-init tools and some debugging
+# tools to retrieve the actual addresses of symbols in the kernel.
+#
+# readprofile starts reading symbols when _stext is found, and
+# continue until it finds a symbol which is not either of 'T', 't',
+# 'W' or 'w'.
+#
+# ---------------------------------------------------------------------------
+# Ignored symbol types
+#
+
+# a: local absolute symbols
+# N: debugging symbols
+# U: undefined global symbols
+# w: local weak symbols
+/ [aNUw] /d
+
+# ---------------------------------------------------------------------------
+# Ignored prefixes
+#  (do not forget a space before each pattern)
+
+# local symbols for ARM, MIPS, etc.
+/ \$/d
+
+# local labels, .LBB, .Ltmpxxx, .L__unnamed_xx, .LASANPC, etc.
+/ \.L/d
+
+# arm64 EFI stub namespace
+/ __efistub_/d
+
+# arm64 local symbols in PIE namespace
+/ __pi_\\$/d
+/ __pi_\.L/d
+
+# arm64 local symbols in non-VHE KVM namespace
+/ __kvm_nvhe_\$/d
+/ __kvm_nvhe_\.L/d
+
+# lld arm/aarch64/mips thunks
+/ __[[:alnum:]]*Thunk_/d
+
+# CFI type identifiers
+/ __kcfi_typeid_/d
+/ __kvm_nvhe___kcfi_typeid_/d
+/ __pi___kcfi_typeid_/d
+
+# CRC from modversions
+/ __crc_/d
+
+# EXPORT_SYMBOL (symbol name)
+/ __kstrtab_/d
+
+# EXPORT_SYMBOL (namespace)
+/ __kstrtabns_/d
+
+# MODULE_DEVICE_TABLE (symbol name)
+/ __mod_device_table__/d
+
+# ---------------------------------------------------------------------------
+# Ignored suffixes
+#  (do not forget '$' after each pattern)
+
+# arm
+/_from_arm$/d
+/_from_thumb$/d
+/_veneer$/d
+
+# ---------------------------------------------------------------------------
+# Ignored symbols (exact match)
+#  (do not forget a space before and '$' after each pattern)
+
+# for LoongArch?
+/ L0$/d
+
+# ppc
+/ _SDA_BASE_$/d
+/ _SDA2_BASE_$/d
+
+# MODULE_INFO()
+/ __UNIQUE_ID_modinfo[0-9]*$/d
+
+# ---------------------------------------------------------------------------
+# Ignored patterns
+#  (symbols that contain the pattern are ignored)
+
+# ppc stub
+/\.long_branch\./d
+/\.plt_branch\./d