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CVE-2019-7573, CVE-2019-7576: Fix buffer overreads in InitMS_ADPCM

If MS ADPCM format chunk was too short, InitMS_ADPCM() parsing it
could read past the end of chunk data. This patch fixes it.

CVE-2019-7573
https://bugzilla.libsdl.org/show_bug.cgi?id=4491
CVE-2019-7576
https://bugzilla.libsdl.org/show_bug.cgi?id=4490

Signed-off-by: Petr P?sa? <ppisar@redhat.com>
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ppisar committed Jun 10, 2019
1 parent f22cbe4 commit 9e69d60b0b724e44637b3e9101758fb385114b69
Showing with 10 additions and 3 deletions.
  1. +10 −3 src/audio/SDL_wave.c
@@ -44,12 +44,13 @@ static struct MS_ADPCM_decoder {
struct MS_ADPCM_decodestate state[2];
} MS_ADPCM_state;

static int InitMS_ADPCM(WaveFMT *format)
static int InitMS_ADPCM(WaveFMT *format, int length)
{
Uint8 *rogue_feel;
Uint8 *rogue_feel, *rogue_feel_end;
int i;

/* Set the rogue pointer to the MS_ADPCM specific data */
if (length < sizeof(*format)) goto too_short;
MS_ADPCM_state.wavefmt.encoding = SDL_SwapLE16(format->encoding);
MS_ADPCM_state.wavefmt.channels = SDL_SwapLE16(format->channels);
MS_ADPCM_state.wavefmt.frequency = SDL_SwapLE32(format->frequency);
@@ -58,9 +59,11 @@ static int InitMS_ADPCM(WaveFMT *format)
MS_ADPCM_state.wavefmt.bitspersample =
SDL_SwapLE16(format->bitspersample);
rogue_feel = (Uint8 *)format+sizeof(*format);
rogue_feel_end = (Uint8 *)format + length;
if ( sizeof(*format) == 16 ) {
rogue_feel += sizeof(Uint16);
}
if (rogue_feel + 4 > rogue_feel_end) goto too_short;
MS_ADPCM_state.wSamplesPerBlock = ((rogue_feel[1]<<8)|rogue_feel[0]);
rogue_feel += sizeof(Uint16);
MS_ADPCM_state.wNumCoef = ((rogue_feel[1]<<8)|rogue_feel[0]);
@@ -70,12 +73,16 @@ static int InitMS_ADPCM(WaveFMT *format)
return(-1);
}
for ( i=0; i<MS_ADPCM_state.wNumCoef; ++i ) {
if (rogue_feel + 4 > rogue_feel_end) goto too_short;
MS_ADPCM_state.aCoeff[i][0] = ((rogue_feel[1]<<8)|rogue_feel[0]);
rogue_feel += sizeof(Uint16);
MS_ADPCM_state.aCoeff[i][1] = ((rogue_feel[1]<<8)|rogue_feel[0]);
rogue_feel += sizeof(Uint16);
}
return(0);
too_short:
SDL_SetError("Unexpected length of a chunk with a MS ADPCM format");
return(-1);
}

static Sint32 MS_ADPCM_nibble(struct MS_ADPCM_decodestate *state,
@@ -495,7 +502,7 @@ SDL_AudioSpec * SDL_LoadWAV_RW (SDL_RWops *src, int freesrc,
break;
case MS_ADPCM_CODE:
/* Try to understand this */
if ( InitMS_ADPCM(format) < 0 ) {
if ( InitMS_ADPCM(format, lenread) < 0 ) {
was_error = 1;
goto done;
}

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