From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 2BCD246081 for ; Wed, 2 Aug 2023 00:01:58 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 6138768C55A; Wed, 2 Aug 2023 03:01:45 +0300 (EEST) Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [217.70.183.193]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 431D468BE6F for ; Wed, 2 Aug 2023 03:01:38 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id 7E1CC240002 for ; Wed, 2 Aug 2023 00:01:37 +0000 (UTC) From: Michael Niedermayer To: FFmpeg development discussions and patches Date: Wed, 2 Aug 2023 02:01:34 +0200 Message-Id: <20230802000135.26482-2-michael@niedermayer.cc> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230802000135.26482-1-michael@niedermayer.cc> References: <20230802000135.26482-1-michael@niedermayer.cc> X-GND-Sasl: michael@niedermayer.cc Subject: [FFmpeg-devel] [PATCH 2/3] avcodec/jpeg2000htdec: Consolidate jpeg2000 spec bits in jpeg2000_bitbuf_refill_backwards() X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: Code should make more sense now Fixes: out of array access Fixes: 58299/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-6627570448465920 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/jpeg2000htdec.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/libavcodec/jpeg2000htdec.c b/libavcodec/jpeg2000htdec.c index 2b082b3b2f..3985783f3a 100644 --- a/libavcodec/jpeg2000htdec.c +++ b/libavcodec/jpeg2000htdec.c @@ -159,21 +159,14 @@ static int jpeg2000_bitbuf_refill_backwards(StateVars *buffer, const uint8_t *ar */ position -= 4; - tmp = AV_RB32(&array[position + 1]); - - if (buffer->pos < 4){ - /* mask un-needed bits if we are close to input end */ - uint64_t mask = (1ull << (buffer->pos + 1) * 8) - 1; - tmp &= mask; - } - /** * Unstuff bits. Load a temporary byte, which precedes the position we * currently at, to ensure that we can also un-stuff if the stuffed bit is * the bottom most bits. */ - tmp <<= 8; - tmp |= array[buffer->pos + 1]; + + for(int i = FFMAX(0, position + 1); i <= buffer->pos + 1; i++) + tmp = 256*tmp + array[i]; if ((tmp & 0x7FFF000000) > 0x7F8F000000) { tmp &= 0x7FFFFFFFFF; -- 2.17.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".