Codecs: mp4: Fix seek in files with single element in lookup_table

lookup_table offset shouldn't be zero terminated.
And fix possible out of bound access.

Change-Id: I212a5fcc1868a2ca519b0052b170e836276fe9de

2 files changed, 8 insertions, 8 deletions

diff --git a/lib/rbcodec/codecs/libm4a/demux.c b/lib/rbcodec/codecs/libm4a/demux.c
index 8a424c5187..47cce9857f 100644
--- a/lib/rbcodec/codecs/libm4a/demux.c
+++ b/lib/rbcodec/codecs/libm4a/demux.c
@@ -524,7 +524,7 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
     stream_seek(qtmovie->stream, qtmovie->res->sample_to_chunk_offset);
     stream_read_sample_to_chunk(qtmovie->stream, &old_first, &old_frame);
     stream_read_sample_to_chunk(qtmovie->stream, &new_first, &new_frame);
-    for (k = 1; k < numentries; ++k)
+    for (k = 1; k < numentries + 1; ++k)
     {
         for (; i < qtmovie->res->num_sample_to_chunks; ++i)
         {
@@ -548,9 +548,11 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
             qtmovie->res->lookup_table[idx++].sample = frame + (k - old_first) * old_frame;
         }
     }
-    /* zero-terminate the lookup table */
-    qtmovie->res->lookup_table[idx].sample = 0;
-    qtmovie->res->lookup_table[idx].offset = 0;
+    /* zero-terminate sample if it wasn't calculated */
+    if (idx < fit_numentries)
+    {
+        qtmovie->res->lookup_table[idx].sample = 0;
+    }
 
     stream_seek(qtmovie->stream, current_offset);
     if (size_remaining)
diff --git a/lib/rbcodec/codecs/libm4a/m4a.c b/lib/rbcodec/codecs/libm4a/m4a.c
index b63b8bad2c..1672cf300c 100644
--- a/lib/rbcodec/codecs/libm4a/m4a.c
+++ b/lib/rbcodec/codecs/libm4a/m4a.c
@@ -181,8 +181,6 @@ unsigned int m4a_seek(demux_res_t* demux_res, stream_t* stream,
     /* Find the chunk after 'sample_i'. */
     for (chunk = 1; chunk < demux_res->num_lookup_table; ++chunk)
     {
-        if (tco_tab[chunk].offset == 0)
-            break;
         if (tco_tab[chunk].sample > sample_i)
             break;
     }
@@ -287,12 +285,12 @@ unsigned int m4a_seek_raw(demux_res_t* demux_res, stream_t* stream,
 
     /* We know the desired byte offset, search for the chunk right before.
      * Return the associated sample to this chunk as chunk_sample. */
-    for (i=0; i < demux_res->num_lookup_table; ++i)
+    for (i = 1; i < demux_res->num_lookup_table; ++i)
     {
         if (demux_res->lookup_table[i].offset > file_loc)
             break;
     }
-    i = (i>0) ? i-1 : 0; /* We want the last chunk _before_ file_loc. */
+    --i; /* We want the last chunk _before_ file_loc. */
     *lookup_table_idx = i;
     chunk_sample = demux_res->lookup_table[i].sample;
     new_pos      = demux_res->lookup_table[i].offset;