Fix possible out of bounds accesses

Bug: 30074856
Change-Id: I1a1387ed29d2e0d010b0d5d4bb3d29453a3a7666
(cherry picked from commit ee54e6ceb66e16b3c10c4a9fc8fbe5fff9110b62)
(cherry picked from commit 78cc5b2401047d8c8ca77f633d8fa32c94e8e8f5)

Author: Sungsoo Lim

gpsinfo.c

@@ -174,7 +174,7 @@ void ProcessGpsInfo(unsigned char * DirStart, int ByteCountUnused, unsigned char
             unsigned OffsetVal;
             OffsetVal = Get32u(DirEntry+8);
             // If its bigger than 4 bytes, the dir entry contains an offset.
-            if (OffsetVal+ByteCount > ExifLength){
+            if (OffsetVal > UINT32_MAX - ByteCount || OffsetVal+ByteCount > ExifLength){
                 // Bogus pointer offset and / or bytecount value
                 ErrNonfatal("Illegal value pointer for tag %04x", Tag,0);
                 continue;

makernote.c

@@ -62,7 +62,7 @@ void ProcessCanonMakerNoteDir(unsigned char * DirStart, unsigned char * OffsetBa
             unsigned OffsetVal;
             OffsetVal = Get32u(DirEntry+8);
             // If its bigger than 4 bytes, the dir entry contains an offset.
-            if (OffsetVal+ByteCount > ExifLength){
+            if (OffsetVal > UINT32_MAX - ByteCount || OffsetVal+ByteCount > ExifLength){
                 // Bogus pointer offset and / or bytecount value
                 ErrNonfatal("Illegal value pointer for tag %04x", Tag,0);
                 continue;