MPEG4Extractor: still more NULL derefernce fixes

When processing various FourCC values within MP4 media, mLastTrack is accessed
without first ensuring that a track has been encoutered. Check for NULL and
bail out instead of crashing.

Bug: 20139950
Change-Id: I3b86377030d73b3134b8769c590509c4f23d9f19

Signed-off-by: Joshua J. Drake <android-open-source@qoop.org>
Tested-by: Moritz Bandemer <replicant@posteo.mx>

1 files changed, 41 insertions, 0 deletions

diff --git a/media/libstagefright/MPEG4Extractor.cpp b/media/libstagefright/MPEG4Extractor.cpp
index dd1e60b..7bd9b29 100644
--- a/media/libstagefright/MPEG4Extractor.cpp
+++ b/media/libstagefright/MPEG4Extractor.cpp
@@ -729,6 +729,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                     }
                 }
 
+                if (!mLastTrack)
+                    return ERROR_MALFORMED;
+
                 mLastTrack->sampleTable = new SampleTable(mDataSource);
             }
 
@@ -923,6 +926,10 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                 // multiple text display formats. These formats will be used to
                 // display the timed text.
                 const char *mime;
+
+                if (!mLastTrack)
+                    return ERROR_MALFORMED;
+
                 CHECK(mLastTrack->meta->findCString(kKeyMIMEType, &mime));
                 if (strcasecmp(mime, MEDIA_MIMETYPE_TEXT_3GPP)) {
                     // For now we only support a single type of media per track.
@@ -979,6 +986,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
             uint16_t sample_size = U16_AT(&buffer[18]);
             uint32_t sample_rate = U32_AT(&buffer[24]) >> 16;
 
+            if (!mLastTrack)
+                return ERROR_MALFORMED;
+
             if (!strcasecmp(MEDIA_MIMETYPE_AUDIO_AMR_NB,
                             FourCC2MIME(chunk_type))) {
                 // AMR NB audio is always mono, 8kHz
@@ -1057,6 +1067,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
             // printf("*** coding='%s' width=%d height=%d\n",
             //        chunk, width, height);
 
+            if (!mLastTrack)
+                return ERROR_MALFORMED;
+
             mLastTrack->meta->setCString(kKeyMIMEType, FourCC2MIME(chunk_type));
             mLastTrack->meta->setInt32(kKeyWidth, width);
             mLastTrack->meta->setInt32(kKeyHeight, height);
@@ -1292,6 +1305,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                 return ERROR_IO;
             }
 
+            if (!mLastTrack)
+                return ERROR_MALFORMED;
+
             mLastTrack->meta->setData(
                     kKeyAVCC, kTypeAVCC, buffer, chunk_data_size);
 
@@ -1324,6 +1340,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                 return ERROR_IO;
             }
 
+            if (!mLastTrack)
+                return ERROR_MALFORMED;
+
             mLastTrack->meta->setData(kKeyD263, kTypeD263, buffer, chunk_data_size);
 
             *offset += chunk_size;
@@ -1437,6 +1456,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
                 return ERROR_IO;
             }
 
+            if (!mLastTrack)
+                return ERROR_MALFORMED;
+
             uint32_t type = ntohl(buffer);
             // For the 3GPP file format, the handler-type within the 'hdlr' box
             // shall be 'text'. We also want to support 'sbtl' handler type
@@ -1451,6 +1473,9 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
 
         case FOURCC('t', 'x', '3', 'g'):
         {
+            if (!mLastTrack)
+                return ERROR_MALFORMED;
+
             uint32_t type;
             const void *data;
             size_t size = 0;
@@ -1565,6 +1590,9 @@ status_t MPEG4Extractor::parseTrackHeader(
         duration = U32_AT(&buffer[20]);
     }
 
+    if (!mLastTrack)
+        return ERROR_MALFORMED;
+
     mLastTrack->meta->setInt32(kKeyTrackID, id);
 
     size_t matrixOffset = dynSize + 16;
@@ -1741,6 +1769,9 @@ status_t MPEG4Extractor::parseMetaData(off64_t offset, size_t size) {
                     int32_t delay, padding;
                     if (sscanf(mLastCommentData,
                                " %*x %x %x %*x", &delay, &padding) == 2) {
+                        if (!mLastTrack)
+                            return ERROR_MALFORMED;
+
                         mLastTrack->meta->setInt32(kKeyEncoderDelay, delay);
                         mLastTrack->meta->setInt32(kKeyEncoderPadding, padding);
                     }
@@ -1870,6 +1901,9 @@ status_t MPEG4Extractor::updateAudioTrackInfoFromESDS_MPEG4Audio(
 
     if (objectTypeIndication == 0xe1) {
         // This isn't MPEG4 audio at all, it's QCELP 14k...
+        if (!mLastTrack)
+            return ERROR_MALFORMED;
+
         mLastTrack->meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_QCELP);
         return OK;
     }
@@ -1913,6 +1947,10 @@ status_t MPEG4Extractor::updateAudioTrackInfoFromESDS_MPEG4Audio(
         objectType = 32 + br.getBits(6);
     }
 
+    if (!mLastTrack)
+        return ERROR_MALFORMED;
+
+
     uint32_t freqIndex = br.getBits(4);
 
     int32_t sampleRate = 0;
@@ -1941,6 +1979,9 @@ status_t MPEG4Extractor::updateAudioTrackInfoFromESDS_MPEG4Audio(
         return ERROR_UNSUPPORTED;
     }
 
+    if (!mLastTrack)
+        return ERROR_MALFORMED;
+
     int32_t prevSampleRate;
     CHECK(mLastTrack->meta->findInt32(kKeySampleRate, &prevSampleRate));