Return null from decoder if GifHeader has error.

library/src/androidTest/java/com/bumptech/glide/load/resource/gif/GifResourceDecoderTest.java

 package com.bumptech.glide.load.resource.gif;
 
+import com.bumptech.glide.gifdecoder.GifDecoder;
 import com.bumptech.glide.gifdecoder.GifHeader;
 import com.bumptech.glide.gifdecoder.GifHeaderParser;
 import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
@@ -49,6 +50,24 @@ public class GifResourceDecoderTest {
         assertNull(decoder.decode(new ByteArrayInputStream(new byte[0]), 100, 100));
     }
 
+    @Test
+    public void testReturnsNullIfParsedHeaderHasFormatError() {
+        GifHeader header = mock(GifHeader.class);
+        when(parser.parseHeader()).thenReturn(header);
+        when(header.getStatus()).thenReturn(GifDecoder.STATUS_FORMAT_ERROR);
+
+        assertNull(decoder.decode(new ByteArrayInputStream(new byte[0]), 100, 100));
+    }
+
+    @Test
+    public void testReturnsNullIfParsedHeaderHasOpenError() {
+        GifHeader header = mock(GifHeader.class);
+        when(parser.parseHeader()).thenReturn(header);
+        when(header.getStatus()).thenReturn(GifDecoder.STATUS_OPEN_ERROR);
+
+        assertNull(decoder.decode(new ByteArrayInputStream(new byte[0]), 100, 100));
+    }
+
     @Test
     public void testReturnsParserToPool() throws IOException {
         when(parserPool.obtain(any(byte[].class))).thenReturn(parser);

library/src/main/java/com/bumptech/glide/load/resource/gif/GifResourceDecoder.java

@@ -60,7 +60,7 @@ public class GifResourceDecoder implements ResourceDecoder<InputStream, GifDrawa
 
     private GifDrawableResource decode(byte[] data, int width, int height, GifHeaderParser parser) {
         final GifHeader header = parser.parseHeader();
-        if (header.getNumFrames() <= 0) {
+        if (header.getNumFrames() <= 0 || header.getStatus() != GifDecoder.STATUS_OK) {
             // If we couldn't decode the GIF, we will end up with a frame count of 0.
             return null;
         }