owl_mmc_probe() invokes dma_request_chan(), which returns a reference of
the specified dma_chan object to "owl_host->dma" with increased refcnt.
When owl_mmc_probe() encounters error, it calls mmc_free_host() to free
the "mmc" memory. Since "owl_host" comes from one of "mmc" fields, this
"free" behavior causes "owl_host" and "owl_host->dma" become invalid, so
the refcount for its field should be decreased to keep refcount balanced
before mmc_free_host() calls.
The reference counting issue happens in several exception handling paths
of owl_mmc_probe(). When those error scenarios occur such as failed to
request irq, the function forgets to decrease the refcnt increased by
dma_request_chan(), causing a refcnt leak.
Fix this issue by jumping to "err_put_dma" label when those error
scenarios occur.
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
---
drivers/mmc/host/owl-mmc.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/mmc/host/owl-mmc.c b/drivers/mmc/host/owl-mmc.c
index 01ffe51f413d..4dc72f5f32f5 100644
--- a/drivers/mmc/host/owl-mmc.c
+++ b/drivers/mmc/host/owl-mmc.c
@@ -635,7 +635,7 @@ static int owl_mmc_probe(struct platform_device *pdev)
owl_host->irq = platform_get_irq(pdev, 0);
if (owl_host->irq < 0) {
ret = -EINVAL;
- goto err_free_host;
+ goto err_put_dma;
}
ret = devm_request_irq(&pdev->dev, owl_host->irq, owl_irq_handler,
@@ -643,19 +643,22 @@ static int owl_mmc_probe(struct platform_device *pdev)
if (ret) {
dev_err(&pdev->dev, "Failed to request irq %d\n",
owl_host->irq);
- goto err_free_host;
+ goto err_put_dma;
}
ret = mmc_add_host(mmc);
if (ret) {
dev_err(&pdev->dev, "Failed to add host\n");
- goto err_free_host;
+ goto err_put_dma;
}
dev_dbg(&pdev->dev, "Owl MMC Controller Initialized\n");
return 0;
+err_put_dma:
+ if (owl_host->dma)
+ dma_release_channel(owl_host->dma);
err_free_host:
mmc_free_host(mmc);
--
2.7.4
