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, 223 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-npcm7xx.c b/drivers/clocksource/timer-npcm7xx.c
new file mode 100644
index 000000000..9af30af5f
--- /dev/null
+++ b/drivers/clocksource/timer-npcm7xx.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2014-2018 Nuvoton Technologies tomer.maimon@nuvoton.com
+ * All rights reserved.
+ *
+ * Copyright 2017 Google, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/clockchips.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include "timer-of.h"
+
+/* Timers registers */
+#define NPCM7XX_REG_TCSR0	0x0 /* Timer 0 Control and Status Register */
+#define NPCM7XX_REG_TICR0	0x8 /* Timer 0 Initial Count Register */
+#define NPCM7XX_REG_TCSR1	0x4 /* Timer 1 Control and Status Register */
+#define NPCM7XX_REG_TICR1	0xc /* Timer 1 Initial Count Register */
+#define NPCM7XX_REG_TDR1	0x14 /* Timer 1 Data Register */
+#define NPCM7XX_REG_TISR	0x18 /* Timer Interrupt Status Register */
+
+/* Timers control */
+#define NPCM7XX_Tx_RESETINT		0x1f
+#define NPCM7XX_Tx_PERIOD		BIT(27)
+#define NPCM7XX_Tx_INTEN		BIT(29)
+#define NPCM7XX_Tx_COUNTEN		BIT(30)
+#define NPCM7XX_Tx_ONESHOT		0x0
+#define NPCM7XX_Tx_OPER			GENMASK(28, 27)
+#define NPCM7XX_Tx_MIN_PRESCALE		0x1
+#define NPCM7XX_Tx_TDR_MASK_BITS	24
+#define NPCM7XX_Tx_MAX_CNT		0xFFFFFF
+#define NPCM7XX_T0_CLR_INT		0x1
+#define NPCM7XX_Tx_CLR_CSR		0x0
+
+/* Timers operating mode */
+#define NPCM7XX_START_PERIODIC_Tx (NPCM7XX_Tx_PERIOD | NPCM7XX_Tx_COUNTEN | \
+					NPCM7XX_Tx_INTEN | \
+					NPCM7XX_Tx_MIN_PRESCALE)
+
+#define NPCM7XX_START_ONESHOT_Tx (NPCM7XX_Tx_ONESHOT | NPCM7XX_Tx_COUNTEN | \
+					NPCM7XX_Tx_INTEN | \
+					NPCM7XX_Tx_MIN_PRESCALE)
+
+#define NPCM7XX_START_Tx (NPCM7XX_Tx_COUNTEN | NPCM7XX_Tx_PERIOD | \
+				NPCM7XX_Tx_MIN_PRESCALE)
+
+#define NPCM7XX_DEFAULT_CSR (NPCM7XX_Tx_CLR_CSR | NPCM7XX_Tx_MIN_PRESCALE)
+
+static int npcm7xx_timer_resume(struct clock_event_device *evt)
+{
+	struct timer_of *to = to_timer_of(evt);
+	u32 val;
+
+	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
+	val |= NPCM7XX_Tx_COUNTEN;
+	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
+
+	return 0;
+}
+
+static int npcm7xx_timer_shutdown(struct clock_event_device *evt)
+{
+	struct timer_of *to = to_timer_of(evt);
+	u32 val;
+
+	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
+	val &= ~NPCM7XX_Tx_COUNTEN;
+	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
+
+	return 0;
+}
+
+static int npcm7xx_timer_oneshot(struct clock_event_device *evt)
+{
+	struct timer_of *to = to_timer_of(evt);
+	u32 val;
+
+	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
+	val &= ~NPCM7XX_Tx_OPER;
+	val |= NPCM7XX_START_ONESHOT_Tx;
+	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
+
+	return 0;
+}
+
+static int npcm7xx_timer_periodic(struct clock_event_device *evt)
+{
+	struct timer_of *to = to_timer_of(evt);
+	u32 val;
+
+	writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
+
+	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
+	val &= ~NPCM7XX_Tx_OPER;
+	val |= NPCM7XX_START_PERIODIC_Tx;
+	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
+
+	return 0;
+}
+
+static int npcm7xx_clockevent_set_next_event(unsigned long evt,
+		struct clock_event_device *clk)
+{
+	struct timer_of *to = to_timer_of(clk);
+	u32 val;
+
+	writel(evt, timer_of_base(to) + NPCM7XX_REG_TICR0);
+	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
+	val |= NPCM7XX_START_Tx;
+	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
+
+	return 0;
+}
+
+static irqreturn_t npcm7xx_timer0_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
+	struct timer_of *to = to_timer_of(evt);
+
+	writel(NPCM7XX_T0_CLR_INT, timer_of_base(to) + NPCM7XX_REG_TISR);
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct timer_of npcm7xx_to = {
+	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
+
+	.clkevt = {
+		.name		    = "npcm7xx-timer0",
+		.features	    = CLOCK_EVT_FEAT_PERIODIC |
+				      CLOCK_EVT_FEAT_ONESHOT,
+		.set_next_event	    = npcm7xx_clockevent_set_next_event,
+		.set_state_shutdown = npcm7xx_timer_shutdown,
+		.set_state_periodic = npcm7xx_timer_periodic,
+		.set_state_oneshot  = npcm7xx_timer_oneshot,
+		.tick_resume	    = npcm7xx_timer_resume,
+		.rating		    = 300,
+	},
+
+	.of_irq = {
+		.handler = npcm7xx_timer0_interrupt,
+		.flags = IRQF_TIMER | IRQF_IRQPOLL,
+	},
+};
+
+static void __init npcm7xx_clockevents_init(void)
+{
+	writel(NPCM7XX_DEFAULT_CSR,
+		timer_of_base(&npcm7xx_to) + NPCM7XX_REG_TCSR0);
+
+	writel(NPCM7XX_Tx_RESETINT,
+		timer_of_base(&npcm7xx_to) + NPCM7XX_REG_TISR);
+
+	npcm7xx_to.clkevt.cpumask = cpumask_of(0);
+	clockevents_config_and_register(&npcm7xx_to.clkevt,
+					timer_of_rate(&npcm7xx_to),
+					0x1, NPCM7XX_Tx_MAX_CNT);
+}
+
+static void __init npcm7xx_clocksource_init(void)
+{
+	u32 val;
+
+	writel(NPCM7XX_DEFAULT_CSR,
+		timer_of_base(&npcm7xx_to) + NPCM7XX_REG_TCSR1);
+	writel(NPCM7XX_Tx_MAX_CNT,
+		timer_of_base(&npcm7xx_to) + NPCM7XX_REG_TICR1);
+
+	val = readl(timer_of_base(&npcm7xx_to) + NPCM7XX_REG_TCSR1);
+	val |= NPCM7XX_START_Tx;
+	writel(val, timer_of_base(&npcm7xx_to) + NPCM7XX_REG_TCSR1);
+
+	clocksource_mmio_init(timer_of_base(&npcm7xx_to) +
+				NPCM7XX_REG_TDR1,
+				"npcm7xx-timer1", timer_of_rate(&npcm7xx_to),
+				200, (unsigned int)NPCM7XX_Tx_TDR_MASK_BITS,
+				clocksource_mmio_readl_down);
+}
+
+static int __init npcm7xx_timer_init(struct device_node *np)
+{
+	struct clk *clk;
+	int ret;
+
+	ret = timer_of_init(np, &npcm7xx_to);
+	if (ret)
+		return ret;
+
+	/* Clock input is divided by PRESCALE + 1 before it is fed */
+	/* to the counter */
+	npcm7xx_to.of_clk.rate = npcm7xx_to.of_clk.rate /
+		(NPCM7XX_Tx_MIN_PRESCALE + 1);
+
+	/* Enable the clock for timer1, if it exists */
+	clk = of_clk_get(np, 1);
+	if (clk) {
+		if (!IS_ERR(clk))
+			clk_prepare_enable(clk);
+		else
+			pr_warn("%pOF: Failed to get clock for timer1: %pe", np, clk);
+	}
+
+	npcm7xx_clocksource_init();
+	npcm7xx_clockevents_init();
+
+	pr_info("Enabling NPCM7xx clocksource timer base: %px, IRQ: %d ",
+		timer_of_base(&npcm7xx_to), timer_of_irq(&npcm7xx_to));
+
+	return 0;
+}
+
+TIMER_OF_DECLARE(wpcm450, "nuvoton,wpcm450-timer", npcm7xx_timer_init);
+TIMER_OF_DECLARE(npcm7xx, "nuvoton,npcm750-timer", npcm7xx_timer_init);
+