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Subject[PATCH] cx18: Fix a sleep-in-atomic bug in snd_cx18_pcm_hw_free
Date
The driver may sleep under a spin lock, and the function call path is:
snd_cx18_pcm_hw_free (acquire the lock by spin_lock_irqsave)
vfree --> may sleep

To fix it, the "substream->runtime->dma_area" is passed to a temporary
value, and mark it NULL when holding the lock. The memory is freed by
vfree through the temporary value outside the lock holding.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
---
drivers/media/pci/cx18/cx18-alsa-pcm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/pci/cx18/cx18-alsa-pcm.c b/drivers/media/pci/cx18/cx18-alsa-pcm.c
index 205a98d..ba83147 100644
--- a/drivers/media/pci/cx18/cx18-alsa-pcm.c
+++ b/drivers/media/pci/cx18/cx18-alsa-pcm.c
@@ -257,14 +257,16 @@ static int snd_cx18_pcm_hw_free(struct snd_pcm_substream *substream)
{
struct snd_cx18_card *cxsc = snd_pcm_substream_chip(substream);
unsigned long flags;
+ unsigned char *dma_area;

spin_lock_irqsave(&cxsc->slock, flags);
if (substream->runtime->dma_area) {
dprintk("freeing pcm capture region\n");
- vfree(substream->runtime->dma_area);
+ dma_area = substream->runtime->dma_area;
substream->runtime->dma_area = NULL;
}
spin_unlock_irqrestore(&cxsc->slock, flags);
+ vfree(dma_area);

return 0;
}
--
1.7.9.5

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