From ef1dbb2df1c0e741486646de40bd638a9c4cd808 Mon Sep 17 00:00:00 2001
From: Erik de Castro Lopo <erikd@mega-nerd.com>
Date: Fri, 14 Apr 2017 15:19:16 +1000
Subject: [PATCH] src/flac.c: Fix a buffer read overflow
A file (generated by a fuzzer) which increased the number of channels
from one frame to the next could cause a read beyond the end of the
buffer provided by libFLAC. Only option is to abort the read.
Closes: https://github.com/erikd/libsndfile/issues/231
---
src/flac.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/src/flac.c b/src/flac.c
index 5a4f8c21..e4f9aaa0 100644
--- a/src/flac.c
+++ b/src/flac.c
@@ -169,6 +169,14 @@ flac_buffer_copy (SF_PRIVATE *psf)
const int32_t* const *buffer = pflac->wbuffer ;
unsigned i = 0, j, offset, channels, len ;
+ if (psf->sf.channels != (int) frame->header.channels)
+ { psf_log_printf (psf, "Error: FLAC frame changed from %d to %d channels\n"
+ "Nothing to do but to error out.\n" ,
+ psf->sf.channels, frame->header.channels) ;
+ psf->error = SFE_FLAC_CHANNEL_COUNT_CHANGED ;
+ return 0 ;
+ } ;
+
/*
** frame->header.blocksize is variable and we're using a constant blocksize
** of FLAC__MAX_BLOCK_SIZE.
@@ -202,7 +210,6 @@ flac_buffer_copy (SF_PRIVATE *psf)
return 0 ;
} ;
-
len = SF_MIN (pflac->len, frame->header.blocksize) ;
if (pflac->remain % channels != 0)
@@ -436,7 +443,7 @@ sf_flac_meta_callback (const FLAC__StreamDecoder * UNUSED (decoder), const FLAC_
{ 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" ,
+ "Nothing to do but to error out.\n" ,
psf->sf.channels, metadata->data.stream_info.channels) ;
psf->error = SFE_FLAC_CHANNEL_COUNT_CHANGED ;
return ;
