[PATCH] soc: fsl: dpio: Free the IRQ before releasing the I/O object

[Myeonghun Pak]

The DPIO interrupt handler accesses priv->io, but dpaa2_dpio_remove()
releases that object before tearing down the interrupts. The IRQ was
requested with devm_request_irq(), and unregister_dpio_irq_handlers()
only clears its affinity hint. fsl_mc_free_irqs() returns IRQ resources
to the MC resource pool without freeing the handler. An interrupt can
therefore access the freed I/O object before devres releases the IRQ.

Explicitly free the managed IRQ before returning its resource to the
pool, and perform IRQ teardown before releasing the I/O object. This
also waits for an in-flight handler while the object is still valid.

This issue was identified during our ongoing static-analysis research
while reviewing kernel code.

Fixes: 993fec7e11ca ("bus: fsl-mc: dpio: add the DPAA2 DPIO object driver")
Assisted-by: LLM
Co-developed-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Myeonghun Pak <mhun512@xxxxxxxxx>
---
 drivers/soc/fsl/dpio/dpio-driver.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/fsl/dpio/dpio-driver.c b/drivers/soc/fsl/dpio/dpio-driver.c
index d5198ffc4455..fa82cdcc4922 100644
--- a/drivers/soc/fsl/dpio/dpio-driver.c
+++ b/drivers/soc/fsl/dpio/dpio-driver.c
@@ -263,6 +263,8 @@ static int dpaa2_dpio_probe(struct fsl_mc_device *dpio_dev)
 static void dpio_teardown_irqs(struct fsl_mc_device *dpio_dev)
 {
 	unregister_dpio_irq_handlers(dpio_dev);
+	devm_free_irq(&dpio_dev->dev, dpio_dev->irqs[0]->virq,
+		      &dpio_dev->dev);
 	fsl_mc_free_irqs(dpio_dev);
 }
 
@@ -276,10 +278,10 @@ static void dpaa2_dpio_remove(struct fsl_mc_device *dpio_dev)
 	priv = dev_get_drvdata(dev);
 	cpu = dpaa2_io_get_cpu(priv->io);
 
-	dpaa2_io_down(priv->io);
-
 	dpio_teardown_irqs(dpio_dev);
 
+	dpaa2_io_down(priv->io);
+
 	cpumask_set_cpu(cpu, cpus_unused_mask);
 
 	err = dpio_open(dpio_dev->mc_io, 0, dpio_dev->obj_desc.id,
-- 
2.47.1