From 1dc8d82da910972d308aebc1ee722044f83b9ccc Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Sat, 29 Oct 2022 18:47:34 +0200
Subject: [PATCH] avcodec/alsdec: Check bits left before block decoding in non
 multi channel coding loop

Fixes: Timeout
Fixes: 52161/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-6440216563154944

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
---
 libavcodec/alsdec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index eab382e74f..4605b2248f 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1660,7 +1660,8 @@ static int read_frame_data(ALSDecContext *ctx, unsigned int ra_frame)
 
     if (!sconf->mc_coding || ctx->js_switch) {
         int independent_bs = !sconf->joint_stereo;
-
+        if (get_bits_left(gb) < 7*channels*ctx->num_blocks)
+            return AVERROR_INVALIDDATA;
         for (c = 0; c < channels; c++) {
             js_blocks[0] = 0;
             js_blocks[1] = 0;