From 9b2eee24768889378032077423cb6a3221a8ad18 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Thu, 14 Feb 2019 15:41:47 +0100
Subject: [PATCH] CVE-2019-7574: Fix a buffer overread in IMA_ADPCM_decode
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If data chunk was shorter than expected based on a WAV format
definition, IMA_ADPCM_decode() tried to read past the data chunk
buffer. This patch fixes it.
CVE-2019-7574
https://bugzilla.libsdl.org/show_bug.cgi?id=4496
Signed-off-by: Petr Písař <ppisar@redhat.com>
---
src/audio/SDL_wave.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/audio/SDL_wave.c b/src/audio/SDL_wave.c
index b6c49de..2968b3d 100644
--- a/src/audio/SDL_wave.c
+++ b/src/audio/SDL_wave.c
@@ -334,7 +334,7 @@ static void Fill_IMA_ADPCM_block(Uint8 *decoded, Uint8 *encoded,
static int IMA_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
{
struct IMA_ADPCM_decodestate *state;
- Uint8 *freeable, *encoded, *decoded;
+ Uint8 *freeable, *encoded, *encoded_end, *decoded;
Sint32 encoded_len, samplesleft;
unsigned int c, channels;
@@ -350,6 +350,7 @@ static int IMA_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
/* Allocate the proper sized output buffer */
encoded_len = *audio_len;
encoded = *audio_buf;
+ encoded_end = encoded + encoded_len;
freeable = *audio_buf;
*audio_len = (encoded_len/IMA_ADPCM_state.wavefmt.blockalign) *
IMA_ADPCM_state.wSamplesPerBlock*
@@ -365,6 +366,7 @@ static int IMA_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
while ( encoded_len >= IMA_ADPCM_state.wavefmt.blockalign ) {
/* Grab the initial information for this block */
for ( c=0; c<channels; ++c ) {
+ if (encoded + 4 > encoded_end) goto invalid_size;
/* Fill the state information for this block */
state[c].sample = ((encoded[1]<<8)|encoded[0]);
encoded += 2;
@@ -387,6 +389,7 @@ static int IMA_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
samplesleft = (IMA_ADPCM_state.wSamplesPerBlock-1)*channels;
while ( samplesleft > 0 ) {
for ( c=0; c<channels; ++c ) {
+ if (encoded + 4 > encoded_end) goto invalid_size;
Fill_IMA_ADPCM_block(decoded, encoded,
c, channels, &state[c]);
encoded += 4;
@@ -398,6 +401,10 @@ static int IMA_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
}
SDL_free(freeable);
return(0);
+invalid_size:
+ SDL_SetError("Unexpected chunk length for an IMA ADPCM decoder");
+ SDL_free(freeable);
+ return(-1);
}
SDL_AudioSpec * SDL_LoadWAV_RW (SDL_RWops *src, int freesrc,
--
2.20.1