diff options
| author | Takashi Iwai <tiwai@suse.de> | 2020-01-29 10:40:41 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-05 13:05:34 +0000 |
| commit | ea4df33739a3decba670a226d435f312bc42a263 (patch) | |
| tree | 1dee715fb50b1197fd19a0dda19297c9291dc621 /sound | |
| parent | 6f8dc95670980e30a1de22c75999d61fd143b693 (diff) | |
ALSA: pcm: Add missing copy ops check before clearing buffer
[ this is a fix specific to 4.4.y and 4.9.y stable trees;
4.14.y and older already contain the right fix ]
The stable 4.4.y and 4.9.y backports of the upstream commit
add9d56d7b37 ("ALSA: pcm: Avoid possible info leaks from PCM stream
buffers") dropped the check of substream->ops->copy_user as copy_user
is a new member that isn't present in the older kernels.
Although upstream drivers should work without this NULL check, it may
cause a regression with a downstream driver that sets some
inaccessible address to runtime->dma_area, leading to a crash at
worst.
Since such drivers must have ops->copy member on older kernels instead
of ops->copy_user, this patch adds the missing check of ops->copy for
fixing the regression.
Reported-and-tested-by: Andreas Schneider <asn@cryptomilk.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/pcm_native.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 2376b09c35cf..23e17a58651b 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -588,7 +588,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream, runtime->boundary *= 2; /* clear the buffer for avoiding possible kernel info leaks */ - if (runtime->dma_area) + if (runtime->dma_area && !substream->ops->copy) memset(runtime->dma_area, 0, runtime->dma_bytes); snd_pcm_timer_resolution_change(substream); |