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From 730c8b917e7deecc3cdf9ac9eb20e2b7e6450356 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
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Date: Mon, 10 Jun 2019 09:25:05 -0700
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Subject: [PATCH 08/11] CVE-2019-7575: Fix a buffer overwrite in
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MS_ADPCM_decode If a WAV format defines shorter audio stream and decoded MS
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ADPCM data chunk is longer, decoding continued past the output audio buffer.
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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This fix is based on a patch from
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<https://bugzilla.libsdl.org/show_bug.cgi?id=4492>.
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https://bugzilla.libsdl.org/show_bug.cgi?id=4493
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CVE-2019-7575
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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--HG--
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branch : SDL-1.2
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---
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src/audio/SDL_wave.c | 13 ++++++++-----
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1 file changed, 8 insertions(+), 5 deletions(-)
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diff --git a/src/audio/SDL_wave.c b/src/audio/SDL_wave.c
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index 88ac2cca6..5f9365147 100644
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--- a/src/audio/SDL_wave.c
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+++ b/src/audio/SDL_wave.c
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@@ -122,7 +122,7 @@ static Sint32 MS_ADPCM_nibble(struct MS_ADPCM_decodestate *state,
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static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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{
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struct MS_ADPCM_decodestate *state[2];
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- Uint8 *freeable, *encoded, *encoded_end, *decoded;
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+ Uint8 *freeable, *encoded, *encoded_end, *decoded, *decoded_end;
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Sint32 encoded_len, samplesleft;
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Sint8 nybble, stereo;
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Sint16 *coeff[2];
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@@ -142,6 +142,7 @@ static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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return(-1);
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}
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decoded = *audio_buf;
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+ decoded_end = decoded + *audio_len;
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/* Get ready... Go! */
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stereo = (MS_ADPCM_state.wavefmt.channels == 2);
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@@ -149,7 +150,7 @@ static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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state[1] = &MS_ADPCM_state.state[stereo];
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while ( encoded_len >= MS_ADPCM_state.wavefmt.blockalign ) {
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/* Grab the initial information for this block */
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- if (encoded + 7 + (stereo ? 7 : 0) > encoded_end) goto too_short;
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+ if (encoded + 7 + (stereo ? 7 : 0) > encoded_end) goto invalid_size;
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state[0]->hPredictor = *encoded++;
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if ( stereo ) {
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state[1]->hPredictor = *encoded++;
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@@ -179,6 +180,7 @@ static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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coeff[1] = MS_ADPCM_state.aCoeff[state[1]->hPredictor];
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/* Store the two initial samples we start with */
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+ if (decoded + 4 + (stereo ? 4 : 0) > decoded_end) goto invalid_size;
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decoded[0] = state[0]->iSamp2&0xFF;
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decoded[1] = state[0]->iSamp2>>8;
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decoded += 2;
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@@ -200,7 +202,8 @@ static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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samplesleft = (MS_ADPCM_state.wSamplesPerBlock-2)*
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MS_ADPCM_state.wavefmt.channels;
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while ( samplesleft > 0 ) {
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- if (encoded + 1 > encoded_end) goto too_short;
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+ if (encoded + 1 > encoded_end) goto invalid_size;
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+ if (decoded + 4 > decoded_end) goto invalid_size;
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nybble = (*encoded)>>4;
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new_sample = MS_ADPCM_nibble(state[0],nybble,coeff[0]);
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@@ -223,8 +226,8 @@ static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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}
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SDL_free(freeable);
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return(0);
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-too_short:
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- SDL_SetError("Too short chunk for a MS ADPCM decoder");
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+invalid_size:
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+ SDL_SetError("Unexpected chunk length for a MS ADPCM decoder");
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SDL_free(freeable);
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return(-1);
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invalid_predictor:
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--
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2.21.0
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