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external-alsa-lib: Commit

external/alsa-lib


Commit MetaInfo

Revision7cea8c156204ebae7c0dc60801dde5ddfa5bb7d0 (tree)
Time2019-02-12 22:37:44
AuthorBrendan Shanks <brendan.shanks@tera...>
CommiterTakashi Iwai

Log Message

pcm: dshare: Fix overflow when slave_hw_ptr rolls over boundary

In snd_pcm_dshare_sync_area() when 'slave_hw_ptr' rolls over
'slave_boundary', the wrong variable is checked ('dshare->slave_hw_ptr' vs
the local 'slave_hw_ptr'). In some cases, this results in 'slave_hw_ptr'
not rolling over correctly. 'slave_size' and 'size' are then much too
large, and the for loop blocks for several minutes copying samples.

This was likely only triggered on 32-bit systems, since the PCM boundary
is computed based on LONG_MAX and is much larger on 64-bit systems.

This same change was made to pcm_dmix in commit
6c7f60f7a982fdba828e4530a9d7aa0aa2b704ae ("Fix boundary overlap”) from
June 2005.

Signed-off-by: Brendan Shanks <brendan.shanks@teradek.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Change Summary

Incremental Difference

--- a/src/pcm/pcm_dshare.c
+++ b/src/pcm/pcm_dshare.c
@@ -121,7 +121,7 @@ static void snd_pcm_dshare_sync_area(snd_pcm_t *pcm)
121121 */
122122 slave_hw_ptr -= slave_hw_ptr % dshare->slave_period_size;
123123 slave_hw_ptr += dshare->slave_buffer_size;
124- if (dshare->slave_hw_ptr > dshare->slave_boundary)
124+ if (slave_hw_ptr >= dshare->slave_boundary)
125125 slave_hw_ptr -= dshare->slave_boundary;
126126 if (slave_hw_ptr < dshare->slave_appl_ptr)
127127 slave_size = slave_hw_ptr + (dshare->slave_boundary - dshare->slave_appl_ptr);
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