From 69aeba8a19ac2fa6e1c9bdfb19229b513f314bb1 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Fri, 4 Dec 2020 00:52:47 +0100
Subject: [PATCH] avcodec/wmaprodec: Check packet size

Fixes: left shift of negative value -25824
Fixes: 27754/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_XMA2_fuzzer-5760255962906624

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/wmaprodec.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libavcodec/wmaprodec.c b/libavcodec/wmaprodec.c
index 88ee5f4015..8024ce1611 100644
--- a/libavcodec/wmaprodec.c
+++ b/libavcodec/wmaprodec.c
@@ -1721,6 +1721,12 @@ static int decode_packet(AVCodecContext *avctx, WMAProDecodeCtx *s,
         }
     } else {
         int frame_size;
+
+        if (avpkt->size < s->next_packet_start) {
+            s->packet_loss = 1;
+            return AVERROR_INVALIDDATA;
+        }
+
         s->buf_bit_size = (avpkt->size - s->next_packet_start) << 3;
         init_get_bits(gb, avpkt->data, s->buf_bit_size);
         skip_bits(gb, s->packet_offset);