hfsplus: refuse to mount volumes larger than 2TB

As found in <http://bugs.debian.org/550010>, hfsplus is using type u32
rather than sector_t for some sector number calculations.

In particular, hfsplus_get_block() does:

        u32 ablock, dblock, mask;
...
        map_bh(bh_result, sb, (dblock << HFSPLUS_SB(sb).fs_shift) + HFSPLUS_SB(sb).blockoffset + (iblock & mask));

I am not confident that I can find and fix all cases where a sector number
may be truncated.  For now, avoid data loss by refusing to mount HFS+
volumes with more than 2^32 sectors (2TB).

[[email protected]: fix 32 and 64-bit issues]
Signed-off-by: Ben Hutchings <[email protected]>
Cc: Eric Sesterhenn <[email protected]>
Cc: Roman Zippel <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/hfsplus/wrapper.c

@@ -99,6 +99,10 @@ int hfsplus_read_wrapper(struct super_block *sb)
 
 	if (hfsplus_get_last_session(sb, &part_start, &part_size))
 		return -EINVAL;
+	if ((u64)part_start + part_size > 0x100000000ULL) {
+		pr_err("hfs: volumes larger than 2TB are not supported yet\n");
+		return -EINVAL;
+	}
 	while (1) {
 		bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
 		if (!bh)