webpdec: correct alloc size check w/use_argb
the allocation is always 4 x width regardless of the presence of alpha
@@ -145,7 +145,7 @@ int ReadWebP(const uint8_t* const data, size_t data_size,
pic->width = bitstream->width;
pic->height = bitstream->height;
if (pic->use_argb) {
- stride = (uint64_t)bitstream->width * (has_alpha ? 4 : 3);
+ stride = (uint64_t)bitstream->width * 4;
} else {
stride = (uint64_t)bitstream->width * (has_alpha ? 5 : 3) / 2;
pic->colorspace = has_alpha ? WEBP_YUV420A : WEBP_YUV420;
