From fd0484aba8e51d16af1e3a880f9b8b857b385eb3 Mon Sep 17 00:00:00 2001

From: Erik de Castro Lopo <erikd@mega-nerd.com>

Date: Wed, 12 Apr 2017 19:45:30 +1000

Subject: [PATCH] FLAC: Fix a buffer read overrun

Buffer read overrun occurs when reading a FLAC file that switches

from 2 channels to one channel mid-stream. Only option is to

abort the read.

Closes: https://github.com/erikd/libsndfile/issues/230

---

 src/common.h  |  1 +

 src/flac.c    | 13 +++++++++++++

 src/sndfile.c |  1 +

 3 files changed, 15 insertions(+)

diff --git a/src/common.h b/src/common.h

index 0bd810c3..e2669b6a 100644

--- a/src/common.h

+++ b/src/common.h

@@ -725,6 +725,7 @@ enum

 	SFE_FLAC_INIT_DECODER,

 	SFE_FLAC_LOST_SYNC,

 	SFE_FLAC_BAD_SAMPLE_RATE,

+	SFE_FLAC_CHANNEL_COUNT_CHANGED,

 	SFE_FLAC_UNKOWN_ERROR,

 	SFE_WVE_NOT_WVE,

diff --git a/src/flac.c b/src/flac.c

index 84de0e26..986a7b8f 100644

--- a/src/flac.c

+++ b/src/flac.c

@@ -434,6 +434,19 @@ sf_flac_meta_callback (const FLAC__StreamDecoder * UNUSED (decoder), const FLAC_

 	switch (metadata->type)

 	{	case FLAC__METADATA_TYPE_STREAMINFO :

+			if (psf->sf.channels > 0 && psf->sf.channels != (int) metadata->data.stream_info.channels)

+			{	psf_log_printf (psf, "Error: FLAC stream changed from %d to %d channels\n"

+									"Nothing to be but to error out.\n" ,

+									psf->sf.channels, metadata->data.stream_info.channels) ;

+				psf->error = SFE_FLAC_CHANNEL_COUNT_CHANGED ;

+				return ;

+				} ;

+

+			if (psf->sf.channels > 0 && psf->sf.samplerate != (int) metadata->data.stream_info.sample_rate)

+			{	psf_log_printf (psf, "Warning: FLAC stream changed sample rates from %d to %d.\n"

+									"Carrying on as if nothing happened.",

+									psf->sf.samplerate, metadata->data.stream_info.sample_rate) ;

+				} ;

 			psf->sf.channels = metadata->data.stream_info.channels ;

 			psf->sf.samplerate = metadata->data.stream_info.sample_rate ;

 			psf->sf.frames = metadata->data.stream_info.total_samples ;

diff --git a/src/sndfile.c b/src/sndfile.c

index 41875610..e2a87be8 100644

--- a/src/sndfile.c

+++ b/src/sndfile.c

@@ -245,6 +245,7 @@ ErrorStruct SndfileErrors [] =

 	{	SFE_FLAC_INIT_DECODER	, "Error : problem with initialization of the flac decoder." },

 	{	SFE_FLAC_LOST_SYNC		, "Error : flac decoder lost sync." },

 	{	SFE_FLAC_BAD_SAMPLE_RATE, "Error : flac does not support this sample rate." },

+	{	SFE_FLAC_CHANNEL_COUNT_CHANGED, "Error : flac channel changed mid stream." },

 	{	SFE_FLAC_UNKOWN_ERROR	, "Error : unknown error in flac decoder." },

 	{	SFE_WVE_NOT_WVE			, "Error : not a WVE file." },