hfsplus: fix overflow in hfsplus_get_block

For filesystems larger than 2TB the final sector number passed to
map_bh might overflow the range representable in a 32-bit data type.
Make sure we use a sector_t for it and the arithmetics calculating it.

Signed-off-by: Christoph Hellwig <hch@tuxera.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index b1991a2a08e0..b9c1a4b5ba89 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -209,6 +209,7 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock,
         struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
         int res = -EIO;
         u32 ablock, dblock, mask;
+        sector_t sector;
         int was_dirty = 0;
         int shift;
 
@@ -255,10 +256,12 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock,
 done:
         dprint(DBG_EXTENT, "get_block(%lu): %llu - %u\n",
                 inode->i_ino, (long long)iblock, dblock);
+
         mask = (1 << sbi->fs_shift) - 1;
-        map_bh(bh_result, sb,
-                (dblock << sbi->fs_shift) + sbi->blockoffset +
-                        (iblock & mask));
+        sector = ((sector_t)dblock << sbi->fs_shift) +
+                  sbi->blockoffset + (iblock & mask);
+        map_bh(bh_result, sb, sector);
+
         if (create) {
                 set_buffer_new(bh_result);
                 hip->phys_size += sb->s_blocksize;