From 69cd6157644cb0a5c9edd7b5920232c2ca31c151 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= Date: Tue, 12 Mar 2019 16:21:41 +0100 Subject: [PATCH] CVE-2019-7577: Fix a buffer overread in MS_ADPCM_nibble and MS_ADPCM_decode MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If a chunk of RIFF/WAV file with MS ADPCM encoding contains an invalid predictor (a valid predictor's value is between 0 and 6 inclusive), a buffer overread can happen when the predictor is used as an index into an array of MS ADPCM coefficients. The overead happens when indexing MS_ADPCM_state.aCoeff[] array in MS_ADPCM_decode() and later when dereferencing a coef pointer in MS_ADPCM_nibble(). This patch fixes it by checking the MS ADPCM predictor values fit into the valid range. CVE-2019-7577 Reproducer: https://bugzilla.libsdl.org/show_bug.cgi?id=4492 Signed-off-by: Petr Písař --- src/audio/SDL_wave.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/audio/SDL_wave.c b/src/audio/SDL_wave.c index 08f65cb..5f93651 100644 --- a/src/audio/SDL_wave.c +++ b/src/audio/SDL_wave.c @@ -155,6 +155,9 @@ static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len) if ( stereo ) { state[1]->hPredictor = *encoded++; } + if (state[0]->hPredictor >= 7 || state[1]->hPredictor >= 7) { + goto invalid_predictor; + } state[0]->iDelta = ((encoded[1]<<8)|encoded[0]); encoded += sizeof(Sint16); if ( stereo ) { @@ -227,6 +230,10 @@ invalid_size: SDL_SetError("Unexpected chunk length for a MS ADPCM decoder"); SDL_free(freeable); return(-1); +invalid_predictor: + SDL_SetError("Invalid predictor value for a MS ADPCM decoder"); + SDL_free(freeable); + return(-1); } struct IMA_ADPCM_decodestate { -- 2.20.1