[PATCH v2 07/11] dmaengine: switchtec-dma: fix use-after-free of swdma_dev in remove()

[Logan Gunthorpe]

dma_async_device_unregister() can drop the last reference on dma_dev
and free swdma_dev synchronously via switchtec_dma_release(), but
switchtec_dma_remove() then uses swdma_dev->bar for iounmap().

Cache bar in a local variable before the unregister call.

Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
Link: https://lore.kernel.org/dmaengine/20260717223431.625EE1F000E9@xxxxxxxxxxxxxxx
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
 drivers/dma/switchtec_dma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/switchtec_dma.c b/drivers/dma/switchtec_dma.c
index 2a1ae27bd1a6..a7e25cb7c0b9 100644
--- a/drivers/dma/switchtec_dma.c
+++ b/drivers/dma/switchtec_dma.c
@@ -1376,6 +1376,7 @@ static int switchtec_dma_probe(struct pci_dev *pdev,
 static void switchtec_dma_remove(struct pci_dev *pdev)
 {
 	struct switchtec_dma_dev *swdma_dev = pci_get_drvdata(pdev);
+	void __iomem *bar = swdma_dev->bar;
 
 	switchtec_dma_chans_release(pdev, swdma_dev);
 
@@ -1388,7 +1389,7 @@ static void switchtec_dma_remove(struct pci_dev *pdev)
 
 	dma_async_device_unregister(&swdma_dev->dma_dev);
 
-	iounmap(swdma_dev->bar);
+	iounmap(bar);
 	pci_release_mem_regions(pdev);
 	pci_disable_device(pdev);
 }
-- 
2.47.3