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[media] ivtv: Fix a sleep-in-atomic bug in snd_ivtv_pcm_hw_free 

The driver may sleep under a spin lock, and the function call path is:
snd_ivtv_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 04:13:54 -03:00 committed by Mauro Carvalho Chehab
parent dde32d4134
commit d989dc20c5
1 changed files with 3 additions and 1 deletions
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4
drivers/media/pci/ivtv/ivtv-alsa-pcm.c
View File

@ -262,14 +262,16 @@ static int snd_ivtv_pcm_hw_free(struct snd_pcm_substream *substream)
{ {
struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream); struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
unsigned long flags; unsigned long flags;
unsigned char *dma_area = NULL;
spin_lock_irqsave(&itvsc->slock, flags); spin_lock_irqsave(&itvsc->slock, flags);
if (substream->runtime->dma_area) { if (substream->runtime->dma_area) {
dprintk("freeing pcm capture region\n"); dprintk("freeing pcm capture region\n");
vfree(substream->runtime->dma_area); dma_area = substream->runtime->dma_area;
substream->runtime->dma_area = NULL; substream->runtime->dma_area = NULL;
} }
spin_unlock_irqrestore(&itvsc->slock, flags); spin_unlock_irqrestore(&itvsc->slock, flags);
vfree(dma_area);
return 0; return 0;
} }