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, 88 insertions, 0 deletions

diff --git a/drivers/clocksource/numachip.c b/drivers/clocksource/numachip.c
new file mode 100644
index 000000000..fdb5fc21f
--- /dev/null
+++ b/drivers/clocksource/numachip.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2015 Numascale AS. All rights reserved.
+ */
+
+#include <linux/clockchips.h>
+
+#include <asm/irq.h>
+#include <asm/numachip/numachip.h>
+#include <asm/numachip/numachip_csr.h>
+
+static DEFINE_PER_CPU(struct clock_event_device, numachip2_ced);
+
+static cycles_t numachip2_timer_read(struct clocksource *cs)
+{
+	return numachip2_read64_lcsr(NUMACHIP2_TIMER_NOW);
+}
+
+static struct clocksource numachip2_clocksource = {
+	.name            = "numachip2",
+	.rating          = 295,
+	.read            = numachip2_timer_read,
+	.mask            = CLOCKSOURCE_MASK(64),
+	.flags           = CLOCK_SOURCE_IS_CONTINUOUS,
+	.mult            = 1,
+	.shift           = 0,
+};
+
+static int numachip2_set_next_event(unsigned long delta, struct clock_event_device *ced)
+{
+	numachip2_write64_lcsr(NUMACHIP2_TIMER_DEADLINE + numachip2_timer(),
+		delta);
+	return 0;
+}
+
+static const struct clock_event_device numachip2_clockevent __initconst = {
+	.name            = "numachip2",
+	.rating          = 400,
+	.set_next_event  = numachip2_set_next_event,
+	.features        = CLOCK_EVT_FEAT_ONESHOT,
+	.mult            = 1,
+	.shift           = 0,
+	.min_delta_ns    = 1250,
+	.min_delta_ticks = 1250,
+	.max_delta_ns    = LONG_MAX,
+	.max_delta_ticks = LONG_MAX,
+};
+
+static void numachip_timer_interrupt(void)
+{
+	struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
+
+	ced->event_handler(ced);
+}
+
+static __init void numachip_timer_each(struct work_struct *work)
+{
+	unsigned local_apicid = __this_cpu_read(x86_cpu_to_apicid) & 0xff;
+	struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
+
+	/* Setup IPI vector to local core and relative timing mode */
+	numachip2_write64_lcsr(NUMACHIP2_TIMER_INT + numachip2_timer(),
+		(3 << 22) | (X86_PLATFORM_IPI_VECTOR << 14) |
+		(local_apicid << 6));
+
+	*ced = numachip2_clockevent;
+	ced->cpumask = cpumask_of(smp_processor_id());
+	clockevents_register_device(ced);
+}
+
+static int __init numachip_timer_init(void)
+{
+	if (numachip_system != 2)
+		return -ENODEV;
+
+	/* Reset timer */
+	numachip2_write64_lcsr(NUMACHIP2_TIMER_RESET, 0);
+	clocksource_register_hz(&numachip2_clocksource, NSEC_PER_SEC);
+
+	/* Setup per-cpu clockevents */
+	x86_platform_ipi_callback = numachip_timer_interrupt;
+	schedule_on_each_cpu(&numachip_timer_each);
+
+	return 0;
+}
+
+arch_initcall(numachip_timer_init);