[PATCH AUTOSEL 4.14 009/108] ASoC: davinci-mcasp: Fix dma_chan refcnt leak when getting dma type

Sasha Levin
2020-06-18T01:53:57Z

From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

[ Upstream commit a697ae6ea56e23397341b027098c1b11d9ab13da ]

davinci_mcasp_get_dma_type() invokes dma_request_chan(), which returns a
reference of the specified dma_chan object to "chan" with increased
refcnt.

When davinci_mcasp_get_dma_type() returns, local variable "chan" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
davinci_mcasp_get_dma_type(). When chan device is NULL, the function
forgets to decrease the refcnt increased by dma_request_chan(), causing
a refcnt leak.

Fix this issue by calling dma_release_channel() when chan device is
NULL.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/1587818916-38730-1-git-send-email-xiyuyang19@fudan.edu.cn
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/soc/davinci/davinci-mcasp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index e10e03800cce..6991718d7c8a 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -1747,8 +1747,10 @@ static int davinci_mcasp_get_dma_type(struct davinci_mcasp *mcasp)
PTR_ERR(chan));
return PTR_ERR(chan);
}
- if (WARN_ON(!chan->device || !chan->device->dev))
+ if (WARN_ON(!chan->device || !chan->device->dev)) {
+ dma_release_channel(chan);
return -EINVAL;
+ }

if (chan->device->dev->of_node)
ret = of_property_read_string(chan->device->dev->of_node,
--
2.25.1