[PATCH] flac: fix segfault when playing corrupt flac files

[Johannes Weißl]

Each FLAC frame has it's own number of channels. If the number of
channles is bigger than defined in STREAMINFO, cmus tries to access
non-existing channels and segfaults. This patch not only fixes the
segfault, but lets cmus decode the corrupt files.

Solves Ubuntu Bug #635231 [1].

[1] https://bugs.launchpad.net/ubuntu/+source/cmus/+bug/635231
---
flac.c | 17 ++++++++++-------
1 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/flac.c b/flac.c
index eec9e60..41dac45 100644
--- a/flac.c
+++ b/flac.c
@@ -187,7 +187,7 @@ static FLAC__StreamDecoderWriteStatus write_cb(const Dec *dec, const FLAC__Frame
struct input_plugin_data *ip_data = data;
struct flac_private *priv = ip_data->private;
int frames, bytes, size, channels, bits, depth;
- int ch, i, j = 0;
+ int ch, nch, i, j = 0;

if (ip_data->sf == 0) {
return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
@@ -213,47 +213,50 @@ static FLAC__StreamDecoderWriteStatus write_cb(const Dec *dec, const FLAC__Frame
}

depth = frame->header.bits_per_sample;
+ if (!depth)
+ depth = bits;
+ nch = frame->header.channels;
if (depth == 8) {
char *b = priv->buf + priv->buf_wpos;

for (i = 0; i < frames; i++) {
for (ch = 0; ch < channels; ch++)
- b[j++] = buf[ch][i];
+ b[j++] = buf[ch % nch][i];
}
} else if (depth == 16) {
int16_t *b = (int16_t *)(priv->buf + priv->buf_wpos);

for (i = 0; i < frames; i++) {
for (ch = 0; ch < channels; ch++)
- b[j++] = LE16(buf[ch][i]);
+ b[j++] = LE16(buf[ch % nch][i]);
}
} else if (depth == 32) {
int32_t *b = (int32_t *)(priv->buf + priv->buf_wpos);

for (i = 0; i < frames; i++) {
for (ch = 0; ch < channels; ch++)
- b[j++] = LE32(buf[ch][i]);
+ b[j++] = LE32(buf[ch % nch][i]);
}
} else if (depth == 12) { /* -> 16 */
int16_t *b = (int16_t *)(priv->buf + priv->buf_wpos);

for (i = 0; i < frames; i++) {
for (ch = 0; ch < channels; ch++)
- b[j++] = LE16(buf[ch][i] << 4);
+ b[j++] = LE16(buf[ch % nch][i] << 4);
}
} else if (depth == 20) { /* -> 32 */
int32_t *b = (int32_t *)(priv->buf + priv->buf_wpos);

for (i = 0; i < frames; i++) {
for (ch = 0; ch < channels; ch++)
- b[j++] = LE32(buf[ch][i] << 12);
+ b[j++] = LE32(buf[ch % nch][i] << 12);
}
} else if (depth == 24) { /* -> 32 */
int32_t *b = (int32_t *)(priv->buf + priv->buf_wpos);

for (i = 0; i < frames; i++) {
for (ch = 0; ch < channels; ch++)
- b[j++] = LE32(buf[ch][i] << 8);
+ b[j++] = LE32(buf[ch % nch][i] << 8);
}
} else {
d_print("bits per sample changed to %d\n", depth);

[Johannes Weißl]

Pulse plugin refuses to output audio files with more than two channels,
while oss and alsa plugins support this. Of course cmus does not handle
multi-channel correctly (no channel map), but at least pulse plays the
stereo subset now.

This is related to Ubuntu Bug #635231 [1]

[1] https://bugs.launchpad.net/ubuntu/+source/cmus/+bug/635231
---
pulse.c | 8 ++++++++
1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/pulse.c b/pulse.c
index fd2af57..75919a4 100644
--- a/pulse.c
+++ b/pulse.c
@@ -30,6 +30,7 @@ static pa_context *pa_ctx;
static pa_stream *pa_s;
static pa_channel_map pa_cmap;
static pa_cvolume pa_vol;
+static pa_sample_spec pa_ss;

/* configuration */
static int pa_restore_volume = 1;
@@ -317,6 +318,12 @@ static int op_pulse_open(sample_format_t sf)
if (!pa_sample_spec_valid(&ss))
return -OP_ERROR_SAMPLE_FORMAT;

+ pa_ss = ss;
+ /* can't be done in op_pulse_mixer_open() since channels is not known
+ * TODO: use correct channel map once sample_format_t is updated */
+ if (!pa_channel_map_init_auto(&pa_cmap, ss.channels, PA_CHANNEL_MAP_ALSA))
+ ret_pa_last_error();
+
rc = __pa_create_context();
if (rc)
return rc;
@@ -477,6 +484,7 @@ static int op_pulse_mixer_set_volume(int l, int r)
if (!pa_s && pa_restore_volume)
return -OP_ERROR_NOT_OPEN;

+ pa_cvolume_set(&pa_vol, pa_ss.channels, (pa_volume_t) ((l + r) / 2));
pa_cvolume_set_position(&pa_vol,
&pa_cmap,
PA_CHANNEL_POSITION_FRONT_LEFT,

[Gregory Petrosyan]

Post by Johannes Weißl
Pulse plugin refuses to output audio files with more than two channels,
while oss and alsa plugins support this. Of course cmus does not handle
multi-channel correctly (no channel map), but at least pulse plays the
stereo subset now.
This is related to Ubuntu Bug #635231 [1]
[1] https://bugs.launchpad.net/ubuntu/+source/cmus/+bug/635231

Merged both patches to both maint and master, thanks!

Gregory