commit 8eddf1ce5736031313004aa4ec87c60e1fe0a5df
author Marco Nelissen <marcone@google.com> Mon Oct 09 14:59:43 2017 -0700
committer Nikoli Cartagena <dargeren@google.com> Tue Nov 28 21:25:14 2017 -0800
tree a56c3497946e3e56417c8fc925ef7ab2512c625c
parent 1648c8d1519adeaccc5ee7d31eccc9fcfb9a07be

Fix edge case when applying id3 unsynchronization

Bug: 63100526
Test: opened poc, other files
Change-Id: I0a51a2a11d0ea84ede0c075de650a7118f0e00c5
(cherry picked from commit 3e70296461c5f260988ab21854a6f43fdafea764)

media/libstagefright/id3/ID3.cpp

diff --git a/media/libstagefright/id3/ID3.cpp b/media/libstagefright/id3/ID3.cpp
index 8d1ad66..58d8b13 100644
--- a/media/libstagefright/id3/ID3.cpp
+++ b/media/libstagefright/id3/ID3.cpp
@@ -392,7 +392,12 @@
                     --mSize;
                     --dataSize;
                 }
-                mData[writeOffset++] = mData[readOffset++];
+                if (i + 1 < dataSize) {
+                    // Only move data if there's actually something to move.
+                    // This handles the special case of the data being only [0xff, 0x00]
+                    // which should be converted to just 0xff if unsynchronization is on.
+                    mData[writeOffset++] = mData[readOffset++];
+                }
             }
             // move the remaining data following this frame
             if (readOffset <= oldSize) {