From 4b4cac39ba7988df9d8def32360dd842b707ba74 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= Date: Sat, 8 Jun 2019 17:57:43 -0700 Subject: [PATCH 01/11] CVE-2019-7572: Fix a buffer overread in IMA_ADPCM_nibble If an IMA ADPCM block contained an initial index out of step table range (loaded in IMA_ADPCM_decode()), IMA_ADPCM_nibble() blindly used this bogus value and that lead to a buffer overread. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch fixes it by moving clamping the index value at the beginning of IMA_ADPCM_nibble() function instead of the end after an update. CVE-2019-7572 https://bugzilla.libsdl.org/show_bug.cgi?id=4495 Signed-off-by: Petr Písař --HG-- branch : SDL-1.2 --- src/audio/SDL_wave.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/src/audio/SDL_wave.c b/src/audio/SDL_wave.c index b4ad6c787..ba1fb5252 100644 --- a/src/audio/SDL_wave.c +++ b/src/audio/SDL_wave.c @@ -264,6 +264,14 @@ static Sint32 IMA_ADPCM_nibble(struct IMA_ADPCM_decodestate *state,Uint8 nybble) }; Sint32 delta, step; + /* Clamp index value. The inital value can be invalid. */ + if ( state->index > 88 ) { + state->index = 88; + } else + if ( state->index < 0 ) { + state->index = 0; + } + /* Compute difference and new sample value */ step = step_table[state->index]; delta = step >> 3; @@ -275,12 +283,6 @@ static Sint32 IMA_ADPCM_nibble(struct IMA_ADPCM_decodestate *state,Uint8 nybble) /* Update index value */ state->index += index_table[nybble]; - if ( state->index > 88 ) { - state->index = 88; - } else - if ( state->index < 0 ) { - state->index = 0; - } /* Clamp output sample */ if ( state->sample > max_audioval ) { -- 2.21.0