Fix several ineffective integer overflow checks

Commit edd4a76 (which addressed bugs 15328708, 15342615, 15342751) added
several integer overflow checks. Unfortunately, those checks fail to take into
account integer promotion rules and are thus themselves subject to an integer
overflow. Cast the sizeof() operator to a uint64_t to force promotion while
multiplying.

Bug: 20139950

(cherry picked from commit e2e812e58e8d2716b00d7d82db99b08d3afb4b32)

Change-Id: I080eb3fa147601f18cedab86e0360406c3963d7b

1 files changed, 3 insertions, 3 deletions

diff --git a/media/libstagefright/SampleTable.cpp b/media/libstagefright/SampleTable.cpp
index 8dfa365..1358582 100644
--- a/media/libstagefright/SampleTable.cpp
+++ b/media/libstagefright/SampleTable.cpp
@@ -330,7 +330,7 @@ status_t SampleTable::setTimeToSampleParams(
     }
 
     mTimeToSampleCount = U32_AT(&header[4]);
-    uint64_t allocSize = mTimeToSampleCount * 2 * sizeof(uint32_t);
+    uint64_t allocSize = mTimeToSampleCount * 2 * (uint64_t)sizeof(uint32_t);
     if (allocSize > SIZE_MAX) {
         return ERROR_OUT_OF_RANGE;
     }
@@ -376,7 +376,7 @@ status_t SampleTable::setCompositionTimeToSampleParams(
     }
 
     mNumCompositionTimeDeltaEntries = numEntries;
-    uint64_t allocSize = numEntries * 2 * sizeof(uint32_t);
+    uint64_t allocSize = numEntries * 2 * (uint64_t)sizeof(uint32_t);
     if (allocSize > SIZE_MAX) {
         return ERROR_OUT_OF_RANGE;
     }
@@ -426,7 +426,7 @@ status_t SampleTable::setSyncSampleParams(off64_t data_offset, size_t data_size)
         ALOGV("Table of sync samples is empty or has only a single entry!");
     }
 
-    uint64_t allocSize = mNumSyncSamples * sizeof(uint32_t);
+    uint64_t allocSize = mNumSyncSamples * (uint64_t)sizeof(uint32_t);
     if (allocSize > SIZE_MAX) {
         return ERROR_OUT_OF_RANGE;
     }