# HG changeset patch
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# User Petr Písař <ppisar@redhat.com>
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# Date 1560183905 25200
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# Mon Jun 10 09:25:05 2019 -0700
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# Branch SDL-1.2
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# Node ID a936f9bd3e381d67d8ddee8b9243f85799ea4798
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# Parent fcbecae427951bac1684baaba2ade68221315140
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CVE-2019-7575: Fix a buffer overwrite in MS_ADPCM_decode
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If a WAV format defines shorter audio stream and decoded MS ADPCM data chunk
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is longer, decoding continued past the output audio buffer.
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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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CVE: CVE-2019-7575
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Upstream-Status: Backport
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Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
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diff -r fcbecae42795 -r a936f9bd3e38 src/audio/SDL_wave.c
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--- a/src/audio/SDL_wave.c Mon Jun 10 09:06:23 2019 -0700
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+++ b/src/audio/SDL_wave.c Mon Jun 10 09:25:05 2019 -0700
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@@ -122,7 +122,7 @@
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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 @@
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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 @@
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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 @@
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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 @@
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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 @@
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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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