From cc263908805662b86237acfb1e6b98d9bbf357d3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= Date: Fri, 15 Feb 2019 10:36:13 +0100 Subject: [PATCH] CVE-2019-7573: Fix a buffer overread in InitMS_ADPCM MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If MS ADPCM format chunk was too short, InitMS_ADPCM() parsing it could read past the and of chunk data. This patch fixes it. CVE-2019-7573 https://bugzilla.libsdl.org/show_bug.cgi?id=4491 Signed-off-by: Petr Písař --- src/audio/SDL_wave.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/src/audio/SDL_wave.c b/src/audio/SDL_wave.c index 91e89e8..1d446ed 100644 --- a/src/audio/SDL_wave.c +++ b/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 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, @@ -485,7 +492,7 @@ 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; } -- 2.20.1