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[media] cx18: Fix a sleep-in-atomic bug in snd_cx18_pcm_hw_free

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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>
[hans.verkuil@cisco.com: removed unnecessary 'if (dma_area)']
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Jia-Ju Bai 2017-06-01 04:17:51 -03:00 committed by Mauro Carvalho Chehab
parent d989dc20c5
commit a3dbff6eec
1 changed files with 3 additions and 1 deletions
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4
drivers/media/pci/cx18/cx18-alsa-pcm.c
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@ -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 = NULL;
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;
}