Get wrong image when reading Bmp due to skipping extra bytes

[XZiar]

sample image(rename it to bmp since github does not allow to upload bmp): bmp-rgba.txt

stb will skip extra bytes before reading actual data:

stb/stb_image.h

Lines 5654 to 5658 in 2e2bef4

	} else {
	int rshift=0,gshift=0,bshift=0,ashift=0,rcount=0,gcount=0,bcount=0,acount=0;
	int z = 0;
	int easy=0;
	stbi__skip(s, info.offset - info.extra_read - info.hsz);

but those bytes have already been skipped earlier when handling plate-size=0 (the bytes_read_so_far is exactly info.extra_read + info.hsz here):

stb/stb_image.h

Lines 5564 to 5582 in 2e2bef4

	if (psize == 0) {
	// accept some number of extra bytes after the header, but if the offset points either to before
	// the header ends or implies a large amount of extra data, reject the file as malformed
	int bytes_read_so_far = s->callback_already_read + (int)(s->img_buffer - s->img_buffer_original);
	int header_limit = 1024; // max we actually read is below 256 bytes currently.
	int extra_data_limit = 256*4; // what ordinarily goes here is a palette; 256 entries*4 bytes is its max size.
	if (bytes_read_so_far <= 0 || bytes_read_so_far > header_limit) {
	return stbi__errpuc("bad header", "Corrupt BMP");
	}
	// we established that bytes_read_so_far is positive and sensible.
	// the first half of this test rejects offsets that are either too small positives, or
	// negative, and guarantees that info.offset >= bytes_read_so_far > 0. this in turn
	// ensures the number computed in the second half of the test can't overflow.
	if (info.offset < bytes_read_so_far || info.offset - bytes_read_so_far > extra_data_limit) {
	return stbi__errpuc("bad offset", "Corrupt BMP");
	} else {
	stbi__skip(s, info.offset - bytes_read_so_far);
	}
	}

seems it's introduced by 1096389
the fix made an extra skip