[PATCH] block: mtip32xx: synchronize ioctls with device removal

[Hongyan Xu <getshell@seu.edu.cn>]

The ioctl handlers only test REMOVE_PENDING before entering
mtip_hw_ioctl(). Removal can set that bit immediately afterwards and free
dd->port in mtip_hw_exit() while an ioctl still dereferences it. An already
open block device can reach the handlers while del_gendisk() is in
progress.

Serialize both native and compat ioctls with removal. Set REMOVE_PENDING
before taking the mutex so new callers fail after an in-flight ioctl has
drained, and hold the mutex until the port has been torn down.

Fixes: 88523a61558a ("block: Add driver for Micron RealSSD pcie flash cards")
Signed-off-by: Hongyan Xu <getshell@seu.edu.cn>
---
 drivers/block/mtip32xx/mtip32xx.c | 7 +++++++
 drivers/block/mtip32xx/mtip32xx.h | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index f214a616386c..113bdb868c46 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -3048,6 +3048,8 @@ static int mtip_block_ioctl(struct block_device *dev,
 	if (!dd)
 		return -ENOTTY;
 
+	guard(mutex)(&dd->ioctl_mutex);
+
 	if (unlikely(test_bit(MTIP_DDF_REMOVE_PENDING_BIT, &dd->dd_flag)))
 		return -ENOTTY;
 
@@ -3086,6 +3088,8 @@ static int mtip_block_compat_ioctl(struct block_device *dev,
 	if (!dd)
 		return -ENOTTY;
 
+	guard(mutex)(&dd->ioctl_mutex);
+
 	if (unlikely(test_bit(MTIP_DDF_REMOVE_PENDING_BIT, &dd->dd_flag)))
 		return -ENOTTY;
 
@@ -3721,6 +3725,7 @@ static int mtip_pci_probe(struct pci_dev *pdev,
 	dd = kzalloc_node(sizeof(struct driver_data), GFP_KERNEL, my_node);
 	if (!dd)
 		return -ENOMEM;
+	mutex_init(&dd->ioctl_mutex);
 
 	/* Attach the private data to this PCI device.  */
 	pci_set_drvdata(pdev, dd);
@@ -3887,6 +3892,7 @@ static void mtip_pci_remove(struct pci_dev *pdev)
 	}
 
 	set_bit(MTIP_DDF_REMOVE_PENDING_BIT, &dd->dd_flag);
+	mutex_lock(&dd->ioctl_mutex);
 
 	if (test_bit(MTIP_DDF_INIT_DONE_BIT, &dd->dd_flag))
 		del_gendisk(dd->disk);
@@ -3915,6 +3921,7 @@ static void mtip_pci_remove(struct pci_dev *pdev)
 
 	/* De-initialize the protocol layer. */
 	mtip_hw_exit(dd);
+	mutex_unlock(&dd->ioctl_mutex);
 
 	if (dd->isr_workq) {
 		destroy_workqueue(dd->isr_workq);
diff --git a/drivers/block/mtip32xx/mtip32xx.h b/drivers/block/mtip32xx/mtip32xx.h
index f7328f19ac5c..0963c07b5845 100644
--- a/drivers/block/mtip32xx/mtip32xx.h
+++ b/drivers/block/mtip32xx/mtip32xx.h
@@ -12,6 +12,7 @@
 #define __MTIP32XX_H__
 
 #include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/rwsem.h>
 #include <linux/ata.h>
 #include <linux/interrupt.h>
@@ -432,6 +433,7 @@ struct driver_data {
 	struct request_queue *queue; /* Our request queue. */
 
 	struct blk_mq_tag_set tags; /* blk_mq tags */
+	struct mutex ioctl_mutex;
 
 	struct mtip_port *port; /* Pointer to the port data structure. */
 
-- 
2.50.1.windows.1