commit bce9a57e0f8c5fb891accd39a88fec7720b98c46
author Dichen Zhang <dichenzhang@google.com> Thu Mar 19 17:27:45 2020 -0700
committer Dichen Zhang <dichenzhang@google.com> Tue Mar 24 21:55:10 2020 +0000
tree 03b2815906d84dde96db9a23432f55966ef82f96
parent 8f612b453b1f2d8d873e615aae281cb047d5a7dc

add trunksize as restriction for function parseClearEncryptedSizes()

Without trunksize as restriction, function parseClearEncryptedSized()
can read the rest of file. If the file has a large number of saiz trunk,
large number of bytes will be copied, which can lead to high cost of
CPU time.

Bug: 124777526
Test: please see #3 and #8 in bug report:
	push senc.mp4 to devices's sdcard
	open photo app
	manuly print log
Change-Id: I854765c82d02d541b92f2658673aa4ce61fb5412
(cherry picked from commit aa15fefa185278a549fd72dd1b79ae73ca5e4436)

media/extractors/mp4/MPEG4Extractor.cpp

diff --git a/media/extractors/mp4/MPEG4Extractor.cpp b/media/extractors/mp4/MPEG4Extractor.cpp
index ce82861..35978e3 100755
--- a/media/extractors/mp4/MPEG4Extractor.cpp
+++ b/media/extractors/mp4/MPEG4Extractor.cpp
@@ -160,8 +160,9 @@
     status_t parseTrackFragmentRun(off64_t offset, off64_t size);
     status_t parseSampleAuxiliaryInformationSizes(off64_t offset, off64_t size);
     status_t parseSampleAuxiliaryInformationOffsets(off64_t offset, off64_t size);
-    status_t parseClearEncryptedSizes(off64_t offset, bool isSubsampleEncryption, uint32_t flags);
-    status_t parseSampleEncryption(off64_t offset);
+    status_t parseClearEncryptedSizes(
+        off64_t offset, bool isSubsampleEncryption, uint32_t flags, off64_t size);
+    status_t parseSampleEncryption(off64_t offset, off64_t size);
     // returns -1 for invalid layer ID
     int32_t parseHEVCLayerId(const uint8_t *data, size_t size);
 
@@ -5188,7 +5189,7 @@
 
         case FOURCC("senc"): {
             status_t err;
-            if ((err = parseSampleEncryption(data_offset)) != OK) {
+            if ((err = parseSampleEncryption(data_offset, chunk_data_size)) != OK) {
                 return err;
             }
             *offset += chunk_size;
@@ -5380,12 +5381,13 @@
     off64_t drmoffset = mCurrentSampleInfoOffsets[0]; // from moof
 
     drmoffset += mCurrentMoofOffset;
+    size -= mCurrentMoofOffset;
 
-    return parseClearEncryptedSizes(drmoffset, false, 0);
+    return parseClearEncryptedSizes(drmoffset, false, 0, size);
 }
 
 status_t MPEG4Source::parseClearEncryptedSizes(
-        off64_t offset, bool isSubsampleEncryption, uint32_t flags) {
+        off64_t offset, bool isSubsampleEncryption, uint32_t flags, off64_t size) {
 
     int32_t ivlength;
     if (!AMediaFormat_getInt32(mFormat, AMEDIAFORMAT_KEY_CRYPTO_DEFAULT_IV_SIZE, &ivlength)) {
@@ -5400,10 +5402,14 @@
 
     uint32_t sampleCount = mCurrentSampleInfoCount;
     if (isSubsampleEncryption) {
+        if(size < 4){
+            return ERROR_MALFORMED;
+        }
         if (!mDataSource->getUInt32(offset, &sampleCount)) {
             return ERROR_IO;
         }
         offset += 4;
+        size -= 4;
     }
 
     // read CencSampleAuxiliaryDataFormats
@@ -5418,11 +5424,15 @@
         }
 
         memset(smpl->iv, 0, 16);
+        if(size < ivlength){
+            return ERROR_MALFORMED;
+        }
         if (mDataSource->readAt(offset, smpl->iv, ivlength) != ivlength) {
             return ERROR_IO;
         }
 
         offset += ivlength;
+        size -= ivlength;
 
         bool readSubsamples;
         if (isSubsampleEncryption) {
@@ -5437,13 +5447,20 @@
 
         if (readSubsamples) {
             uint16_t numsubsamples;
+            if(size < 2){
+                return ERROR_MALFORMED;
+            }
             if (!mDataSource->getUInt16(offset, &numsubsamples)) {
                 return ERROR_IO;
             }
             offset += 2;
+            size -= 2;
             for (size_t j = 0; j < numsubsamples; j++) {
                 uint16_t numclear;
                 uint32_t numencrypted;
+                if(size < 6){
+                    return ERROR_MALFORMED;
+                }
                 if (!mDataSource->getUInt16(offset, &numclear)) {
                     return ERROR_IO;
                 }
@@ -5452,6 +5469,7 @@
                     return ERROR_IO;
                 }
                 offset += 4;
+                size -= 6;
                 smpl->clearsizes.add(numclear);
                 smpl->encryptedsizes.add(numencrypted);
             }
@@ -5464,12 +5482,15 @@
     return OK;
 }
 
-status_t MPEG4Source::parseSampleEncryption(off64_t offset) {
+status_t MPEG4Source::parseSampleEncryption(off64_t offset, off64_t chunk_data_size) {
     uint32_t flags;
+    if(chunk_data_size < 4) {
+        return ERROR_MALFORMED;
+    }
     if (!mDataSource->getUInt32(offset, &flags)) { // actually version + flags
         return ERROR_MALFORMED;
     }
-    return parseClearEncryptedSizes(offset + 4, true, flags);
+    return parseClearEncryptedSizes(offset + 4, true, flags, chunk_data_size - 4);
 }
 
 status_t MPEG4Source::parseTrackFragmentHeader(off64_t offset, off64_t size) {