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, 34 insertions, 0 deletions

diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
new file mode 100644
index 000000000..7b6dd53e8
--- /dev/null
+++ b/drivers/mtd/Makefile
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the memory technology device drivers.
+#
+
+# Core functionality.
+obj-$(CONFIG_MTD)		+= mtd.o
+mtd-y				:= mtdcore.o mtdsuper.o mtdconcat.o mtdpart.o mtdchar.o
+mtd-$(CONFIG_MTD_VIRT_CONCAT)	+= mtd_virt_concat.o
+
+obj-y				+= parsers/
+
+# 'Users' - code which presents functionality to userspace.
+obj-$(CONFIG_MTD_BLKDEVS)	+= mtd_blkdevs.o
+obj-$(CONFIG_MTD_BLOCK)		+= mtdblock.o
+obj-$(CONFIG_MTD_BLOCK_RO)	+= mtdblock_ro.o
+obj-$(CONFIG_FTL)		+= ftl.o
+obj-$(CONFIG_NFTL)		+= nftl.o
+obj-$(CONFIG_INFTL)		+= inftl.o
+obj-$(CONFIG_RFD_FTL)		+= rfd_ftl.o
+obj-$(CONFIG_SSFDC)		+= ssfdc.o
+obj-$(CONFIG_SM_FTL)		+= sm_ftl.o
+obj-$(CONFIG_MTD_OOPS)		+= mtdoops.o
+obj-$(CONFIG_MTD_PSTORE)	+= mtdpstore.o
+obj-$(CONFIG_MTD_SWAP)		+= mtdswap.o
+
+nftl-objs		:= nftlcore.o nftlmount.o
+inftl-objs		:= inftlcore.o inftlmount.o
+
+obj-y		+= chips/ lpddr/ maps/ devices/ nand/ tests/
+
+obj-$(CONFIG_MTD_SPI_NOR)	+= spi-nor/
+obj-$(CONFIG_MTD_UBI)		+= ubi/
+obj-$(CONFIG_MTD_HYPERBUS)	+= hyperbus/