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, 110 insertions, 0 deletions

diff --git a/drivers/clocksource/clps711x-timer.c b/drivers/clocksource/clps711x-timer.c
new file mode 100644
index 000000000..63ae3a691
--- /dev/null
+++ b/drivers/clocksource/clps711x-timer.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Cirrus Logic CLPS711X clocksource driver
+ *
+ *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+enum {
+	CLPS711X_CLKSRC_CLOCKSOURCE,
+	CLPS711X_CLKSRC_CLOCKEVENT,
+};
+
+static void __iomem *tcd;
+
+static u64 notrace clps711x_sched_clock_read(void)
+{
+	return ~readw(tcd);
+}
+
+static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
+{
+	unsigned long rate = clk_get_rate(clock);
+
+	tcd = base;
+
+	clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
+			      clocksource_mmio_readw_down);
+
+	sched_clock_register(clps711x_sched_clock_read, 16, rate);
+}
+
+static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
+					unsigned int irq)
+{
+	struct clock_event_device *clkevt;
+	unsigned long rate;
+
+	clkevt = kzalloc_obj(*clkevt);
+	if (!clkevt)
+		return -ENOMEM;
+
+	rate = clk_get_rate(clock);
+
+	/* Set Timer prescaler */
+	writew(DIV_ROUND_CLOSEST(rate, HZ), base);
+
+	clkevt->name = "clps711x-clockevent";
+	clkevt->rating = 300;
+	clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
+	clkevt->cpumask = cpumask_of(0);
+	clockevents_config_and_register(clkevt, HZ, 0, 0);
+
+	return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
+			   "clps711x-timer", clkevt);
+}
+
+static int __init clps711x_timer_init(struct device_node *np)
+{
+	unsigned int irq = irq_of_parse_and_map(np, 0);
+	struct clk *clock = of_clk_get(np, 0);
+	void __iomem *base = of_iomap(np, 0);
+	int ret = 0;
+
+	if (!base)
+		return -ENOMEM;
+	if (!irq) {
+		ret = -EINVAL;
+		goto unmap_io;
+	}
+	if (IS_ERR(clock)) {
+		ret = PTR_ERR(clock);
+		goto unmap_io;
+	}
+
+	switch (of_alias_get_id(np, "timer")) {
+	case CLPS711X_CLKSRC_CLOCKSOURCE:
+		clps711x_clksrc_init(clock, base);
+		return 0;
+	case CLPS711X_CLKSRC_CLOCKEVENT:
+		ret =  _clps711x_clkevt_init(clock, base, irq);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+unmap_io:
+	iounmap(base);
+	return ret;
+}
+TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);