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).

[akpm@linux-foundation.org: fix 32 and 64-bit issues]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Eric Sesterhenn <snakebyte@gmx.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/hfsplus/wrapper.c b/fs/hfsplus/wrapper.c
index 175d08eacc86..bed78ac8f6d1 100644
--- a/fs/hfsplus/wrapper.c
+++ b/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)