[PATCH] hfsplus: Refuse to mount volumes larger than 2TB

[Ben Hutchings <ben@decadent.org.uk>]

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).

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@kernel.org
---
--- a/fs/hfsplus/wrapper.c
+++ b/fs/hfsplus/wrapper.c
@@ -99,6 +99,10 @@
 
 	if (hfsplus_get_last_session(sb, &part_start, &part_size))
 		return -EINVAL;
+	if (part_start + part_size > 0x100000000) {
+		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)

-- 
Ben Hutchings
Quantity is no substitute for quality, but it's the only one we've got.