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
References: CVE-2017-8361 CVE-2017-8363 CVE-2017-8365 bsc#1036944 bsc#1036945 bsc#1036946

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(+)

--- a/src/common.h
+++ b/src/common.h
@@ -623,6 +623,7 @@ 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,
--- a/src/flac.c
+++ b/src/flac.c
@@ -405,6 +405,19 @@ sf_flac_meta_callback (const FLAC__Strea
 
 	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 ;
--- a/src/sndfile.c
+++ b/src/sndfile.c
@@ -242,6 +242,7 @@ 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." },