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pcm: fix and optimize snd_pcm_areas_copy function

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The memcpy() function in snd_pcm_area_copy() should not be called
with the overlapped areas. Alex discovered - using own LD_PRELOAD checked
for memcpy() input - that the memcpy() is called with src == dst.

For some special plugin combos (rate+softvol+hw for example), the same
areas with same offsets can be asked to be copied (softvol). The collapse
check uses own areas created on heap, causing dst_area == src_area &&
dst_offset == src_offset check bypassed.

Two fixes are in this patch:

- use assert to check the memcpy() input for future triggers
- bypass the snd_pcm_area_copy() call for collapsed identical areas

Reported-by: Alexander Kruppa <akruppa@gmail.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2013-03-20 20:37:50 +01:00
parent 28493d9d69
commit 009193a345
1 changed files with 17 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

28
src/pcm/pcm.c
View file

@ -2711,6 +2711,8 @@ int snd_pcm_area_copy(const snd_pcm_channel_area_t *dst_area, snd_pcm_uframes_t
dst_area->step == (unsigned int) width) {
size_t bytes = samples * width / 8;
samples -= bytes * 8 / width;
assert(src < dst || src >= dst + bytes);
assert(dst < src || dst >= src + bytes);
memcpy(dst, src, bytes);
if (samples == 0)
return 0;
@ -2845,17 +2847,21 @@ int snd_pcm_areas_copy(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_
break;
}
if (chns > 1 && chns * width == step) {
/* Collapse the areas */
snd_pcm_channel_area_t s, d;
s.addr = src_start->addr;
s.first = src_start->first;
s.step = width;
d.addr = dst_start->addr;
d.first = dst_start->first;
d.step = width;
snd_pcm_area_copy(&d, dst_offset * chns,
&s, src_offset * chns,
frames * chns, format);
if (src_offset != dst_offset ||
src_start->addr != dst_start->addr ||
src_start->first != dst_start->first) {
/* Collapse the areas */
snd_pcm_channel_area_t s, d;
s.addr = src_start->addr;
s.first = src_start->first;
s.step = width;
d.addr = dst_start->addr;
d.first = dst_start->first;
d.step = width;
snd_pcm_area_copy(&d, dst_offset * chns,
&s, src_offset * chns,
frames * chns, format);
}
channels -= chns;
} else {
snd_pcm_area_copy(dst_start, dst_offset,