integer overflow -> segfault with ReadRaster

[timaranz]

I naively tried to load an elevation grid which was 16764 x 20264 pixels into a buffer of doubles. Silly me. The first line of DSReadRaster_internal (line 42 of swig\include\Dataset.i) overflows *buf_size = buf_xsize * buf_ysize * (GDALGetDataTypeSize( buf_type ) / 8) * band_list;

became

*buf_size = 16764 * 20264 * 8 * 1;

Need to check for overflow and raise an error if:

buf_xsize > (1 << 31) / (buf_ysize * (GDALGetDataTypeSize( buf_type ) / 8) * band_list))

[Even Rouault]

This is a duplicate of #2140. Closing