SampleTable.cpp: Fixed a regression caused by a fix for bug

28076789.

Detail: Before the original fix
(Id207f369ab7b27787d83f5d8fc48dc53ed9fcdc9) for 28076789, the
code allowed a time-to-sample table size to be 0. The change
made in that fix disallowed such situation, which in fact should
be allowed. This current patch allows it again while maintaining
the security of the previous fix.

Bug: 28288202
Bug: 28076789
Change-Id: I1c9a60c7f0cfcbd3d908f24998dde15d5136a295

2 files changed, 6 insertions, 2 deletions

diff --git a/media/libstagefright/SampleTable.cpp b/media/libstagefright/SampleTable.cpp
index 5344ae4..8df9cb8 100644
--- a/media/libstagefright/SampleTable.cpp
+++ b/media/libstagefright/SampleTable.cpp
@@ -121,6 +121,7 @@ SampleTable::SampleTable(const sp<DataSource> &source)
       mSampleSizeFieldSize(0),
       mDefaultSampleSize(0),
       mNumSampleSizes(0),
+      mHasTimeToSample(false),
       mTimeToSampleCount(0),
       mTimeToSample(),
       mSampleTimeEntries(NULL),
@@ -159,7 +160,7 @@ bool SampleTable::isValid() const {
     return mChunkOffsetOffset >= 0
         && mSampleToChunkOffset >= 0
         && mSampleSizeOffset >= 0
-        && !mTimeToSample.empty();
+        && mHasTimeToSample;
 }
 
 status_t SampleTable::setChunkOffsetParams(
@@ -324,7 +325,7 @@ status_t SampleTable::setSampleSizeParams(
 
 status_t SampleTable::setTimeToSampleParams(
         off64_t data_offset, size_t data_size) {
-    if (!mTimeToSample.empty() || data_size < 8) {
+    if (mHasTimeToSample || data_size < 8) {
         return ERROR_MALFORMED;
     }
 
@@ -364,6 +365,8 @@ status_t SampleTable::setTimeToSampleParams(
     for (size_t i = 0; i < mTimeToSample.size(); ++i) {
         mTimeToSample.editItemAt(i) = ntohl(mTimeToSample[i]);
     }
+
+    mHasTimeToSample = true;
     return OK;
 }
 
diff --git a/media/libstagefright/include/SampleTable.h b/media/libstagefright/include/SampleTable.h
index 3764adb..465f37c 100644
--- a/media/libstagefright/include/SampleTable.h
+++ b/media/libstagefright/include/SampleTable.h
@@ -111,6 +111,7 @@ private:
     uint32_t mDefaultSampleSize;
     uint32_t mNumSampleSizes;
 
+    bool mHasTimeToSample;
     uint32_t mTimeToSampleCount;
     Vector<uint32_t> mTimeToSample;