Prevent divide by zero in WAVExtractor

In the case that mNumChannels, bytesPerSample, or mSampleRate are
zero, a divide by zero occurs. None of these parameters of a WAV
file should ever be zero. Check that they aren't and return an error
otherwise.

Bug: 23285883

Change-Id: Id67b8620944405ca59572221f6f1c2b19c363e69

1 files changed, 10 insertions, 2 deletions

diff --git a/media/libstagefright/WAVExtractor.cpp b/media/libstagefright/WAVExtractor.cpp
index cc1d7ce..62bb416 100644
--- a/media/libstagefright/WAVExtractor.cpp
+++ b/media/libstagefright/WAVExtractor.cpp
@@ -315,9 +315,17 @@ status_t WAVExtractor::init() {
                         1000000LL * (mDataSize / 65 * 320) / 8000;
                 } else {
                     size_t bytesPerSample = mBitsPerSample >> 3;
+
+                    if (!bytesPerSample || !mNumChannels)
+                        return ERROR_MALFORMED;
+
+                    size_t num_samples = mDataSize / (mNumChannels * bytesPerSample);
+
+                    if (!mSampleRate)
+                        return ERROR_MALFORMED;
+
                     durationUs =
-                        1000000LL * (mDataSize / (mNumChannels * bytesPerSample))
-                            / mSampleRate;
+                        1000000LL * num_samples / mSampleRate;
                 }
 
                 mTrackMeta->setInt64(kKeyDuration, durationUs);