Fix decoding of Extra Records that have empty Data.

diff --git a/src/liblzma/common/metadata_decoder.c b/src/liblzma/common/metadata_decoder.c
index 298a424..9704575 100644 (file)
--- a/src/liblzma/common/metadata_decoder.c
+++ b/src/liblzma/common/metadata_decoder.c
@@ -356,7 +356,18 @@ process(lzma_coder *coder, lzma_allocator *allocator)
        case SEQ_EXTRA_SIZE:
        case SEQ_EXTRA_DUMMY_SIZE:
                read_vli(coder->tmp);
-               ++coder->sequence;
+
+               if (coder->tmp == 0) {
+                       // We have no Data in the Extra Record. Don't
+                       // allocate any memory for it. Go back to
+                       // SEQ_EXTRA_ALLOC or SEQ_EXTRA_DUMMY_ALLOC.
+                       coder->tmp = 0;
+                       coder->sequence -= 2;
+                       coder->todo_count = 0;
+               } else {
+                       ++coder->sequence;
+               }
+
                break;
 
        case SEQ_EXTRA_DATA_ALLOC: {