From be4fb282f9fb00d9c267dcc477745e2e468e758f Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Fri, 26 Jul 2019 15:26:08 +0200 Subject: [PATCH] avcodec/alsdec: Check for block_length <= 0 in read_var_block_data() Fixes: left shift of negative value -1 Fixes: 15719/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5685731105701888 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/alsdec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c index 6b5774175b..d4451482a4 100644 --- a/libavcodec/alsdec.c +++ b/libavcodec/alsdec.c @@ -657,7 +657,7 @@ static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd) // do not continue in case of a damaged stream since // block_length must be evenly divisible by sub_blocks - if (bd->block_length & (sub_blocks - 1)) { + if (bd->block_length & (sub_blocks - 1) || bd->block_length <= 0) { av_log(avctx, AV_LOG_WARNING, "Block length is not evenly divisible by the number of subblocks.\n"); return AVERROR_INVALIDDATA;