[PATCH v1] mtd: rawnand: r852: Prevent card work during removal

[Yibo Tan]

r852_irq() queues card_detect_work when card state changes.  r852_remove()
currently cancels that work and destroys its private workqueue before it
disables and frees the IRQ.

A card event in this interval can queue delayed work on the destroyed
workqueue.  Its timer is part of struct r852_device, which is freed later
in r852_remove().  KASAN reported a use-after-free in the timer code when
the card interrupt occurred in this interval.  The same test completed
without a kernel diagnostic after this change.

Set a removal flag while holding irqlock before cancelling the work.  The
IRQ handler still acknowledges and disables card events, but does not
queue more card-detect work during removal.  The lock ensures that work
queued before the flag is cancelled and later interrupts skip the queue.

Fixes: 67e054e91924 ("mtd: nand: Add driver for Ricoh xD/SmartMedia reader")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: Codex:GPT-5
Signed-off-by: Yibo Tan <lhfff@xxxxxxxxxx>
---
 drivers/mtd/nand/raw/r852.c | 7 +++++++
 drivers/mtd/nand/raw/r852.h | 1 +
 2 files changed, 8 insertions(+)

diff --git a/drivers/mtd/nand/raw/r852.c b/drivers/mtd/nand/raw/r852.c
index 92c47d351c27..6170a481cb1f 100644
--- a/drivers/mtd/nand/raw/r852.c
+++ b/drivers/mtd/nand/raw/r852.c
@@ -747,6 +747,9 @@ static irqreturn_t r852_irq(int irq, void *data)
 		/* this will timeout DMA if active, but better that garbage */
 		r852_disable_irqs(dev);
 
+		if (dev->removing)
+			goto out;
+
 		if (dev->card_unstable)
 			goto out;
 
@@ -977,6 +980,10 @@ static void r852_remove(struct pci_dev *pci_dev)
 {
 	struct r852_device *dev = pci_get_drvdata(pci_dev);
 
+	spin_lock_irq(&dev->irqlock);
+	dev->removing = true;
+	spin_unlock_irq(&dev->irqlock);
+
 	/* Stop detect workqueue -
 		we are going to unregister the device anyway*/
 	cancel_delayed_work_sync(&dev->card_detect_work);
diff --git a/drivers/mtd/nand/raw/r852.h b/drivers/mtd/nand/raw/r852.h
index 96fe301d15da..5c931880c2f4 100644
--- a/drivers/mtd/nand/raw/r852.h
+++ b/drivers/mtd/nand/raw/r852.h
@@ -131,6 +131,7 @@ struct r852_device {
 	int card_detected;		/* card detected in slot */
 	int card_unstable;		/* whenever the card is inserted,
 					   is not known yet */
+	bool removing;			/* do not queue card work during removal */
 	int readonly;			/* card is readonly */
 	int sm;				/* Is card smartmedia */
 
-- 
2.39.5