[PATCH v4 12/12] dmaengine: plx_dma: fix NULL pointer deref in plx_dma_isr()

plx_dma_create() registered the interrupt handler with request_irq()
before initializing plxdev->bar. If the device raised an interrupt in
that window, plx_dma_isr() would dereference the still-NULL bar.

Move the bar assignment ahead of request_irq() so everything the
handler can touch is initialized before it can run.

Reported-by: Sangyun Kim <[email protected]>
Reported-by: Kyungwook Boo <[email protected]>
Link: https://lore.kernel.org/all/[email protected]
Fixes: c2dbcaa8c672 ("dmaengine: plx-dma: Implement hardware initialization and cleanup")
Reviewed-by: Frank Li <[email protected]>
Signed-off-by: Logan Gunthorpe <[email protected]>
---
 drivers/dma/plx_dma.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/plx_dma.c b/drivers/dma/plx_dma.c
index 84941a918b01..409898e92c32 100644
--- a/drivers/dma/plx_dma.c
+++ b/drivers/dma/plx_dma.c
@@ -504,17 +504,17 @@ static int plx_dma_create(struct pci_dev *pdev)
 	if (!plxdev)
 		return -ENOMEM;
 
-	rc = request_irq(pci_irq_vector(pdev, 0), plx_dma_isr, 0,
-			 KBUILD_MODNAME, plxdev);
-	if (rc)
-		goto free_plx;
-
 	spin_lock_init(&plxdev->ring_lock);
 	tasklet_setup(&plxdev->desc_task, plx_dma_desc_task);
 
 	RCU_INIT_POINTER(plxdev->pdev, pdev);
 	plxdev->bar = pcim_iomap_table(pdev)[0];
 
+	rc = request_irq(pci_irq_vector(pdev, 0), plx_dma_isr, 0,
+			 KBUILD_MODNAME, plxdev);
+	if (rc)
+		goto free_plx;
+
 	dma = &plxdev->dma_dev;
 	INIT_LIST_HEAD(&dma->channels);
 	dma_cap_set(DMA_MEMCPY, dma->cap_mask);
-- 
2.47.3