commit 7fe9ce5daa3208dad0a8480c5b11e90e9745e5f7
author James Zern <jzern@google.com> Sat Apr 22 13:11:16 2017 -0700
committer James Zern <jzern@google.com> Fri Apr 28 02:14:48 2017 +0000
tree cbfb0fc850b4975734bc35f35eaf3e327c8df21e
parent a1ee74f727ab2d50bcaccbb33f3607156f26f3fd

webm_read_frame: avoid NULL dereference

block may be NULL with block_entry_eos or from return of GetBlock()

Change-Id: Ia0dd3ffa46305ee70efcdc55c05c2ad24efc993b

webmdec.cc

diff --git a/webmdec.cc b/webmdec.cc
index 5ee345d..39ecef7 100644
--- a/webmdec.cc
+++ b/webmdec.cc
@@ -164,10 +164,11 @@
     }
     if (get_new_block) {
       block = block_entry->GetBlock();
+      if (block == NULL) return -1;
       webm_ctx->block_frame_index = 0;
     }
-  } while (block->GetTrackNumber() != webm_ctx->video_track_index ||
-           block_entry_eos);
+  } while (block_entry_eos ||
+           block->GetTrackNumber() != webm_ctx->video_track_index);
 
   webm_ctx->cluster = cluster;
   webm_ctx->block_entry = block_entry;