From 52c2660c26beaaccf903759c18bb758e9f18a470 Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Thu, 3 Aug 2017 13:47:15 +0300
Subject: [PATCH] Make sure at least one bit exists before reading further in
 FDKreadBit

Fixes: 2709/clusterfuzz-testcase-minimized-6160249369133056

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
---
 libFDK/include/FDK_bitstream.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libFDK/include/FDK_bitstream.h b/libFDK/include/FDK_bitstream.h
index d47a750..19bc864 100644
--- a/libFDK/include/FDK_bitstream.h
+++ b/libFDK/include/FDK_bitstream.h
@@ -277,11 +277,15 @@ FDK_INLINE UINT FDKreadBit(HANDLE_FDK_BITSTREAM hBitStream)
       hBitStream->CacheWord = FDK_get32 (&hBitStream->hBitBuf);
       hBitStream->BitsInCache = CACHE_BITS;
     }
-    else
+    else if (validBits > 0)
     {
       hBitStream->CacheWord = FDK_get (&hBitStream->hBitBuf,validBits);
       hBitStream->BitsInCache = validBits;
     }
+    else
+    {
+      return 0;
+    }
   }
   hBitStream->BitsInCache--;