ext4: Fix overflow caused by missing cast in ext4_fallocate()

The logical block number in map.l_blk is a __u32, and so before we
shift it left, by the block size, we neeed cast it to a 64-bit size.

Otherwise i_size can be corrupted on an ENOSPC.

# df -T /mnt/mp1
Filesystem    Type   1K-blocks      Used Available Use% Mounted on
/dev/sda6     ext4     9843276    153056   9190200   2% /mnt/mp1
# fallocate -o 0 -l 2199023251456 /mnt/mp1/testfile
fallocate: /mnt/mp1/testfile: fallocate failed: No space left on device
# stat /mnt/mp1/testfile
  File: `/mnt/mp1/testfile'
  Size: 4293656576	Blocks: 19380440   IO Block: 4096   regular file
Device: 806h/2054d	Inode: 12          Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2011-07-25 13:01:31.414490496 +0900
Modify: 2011-07-25 13:01:31.414490496 +0900
Change: 2011-07-25 13:01:31.454490495 +0900

Signed-off-by: Utako Kusaka <u-kusaka@wm.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
--
 fs/ext4/extents.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index a25bbdc7d493896b19ea4d0748b3397b7b97fb99..57cf568a98ab652afcfe3581d093d5f2b5758689 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3824,7 +3824,7 @@ retry:
                                                blkbits) >> blkbits))
                        new_size = offset + len;
                else
-                       new_size = (map.m_lblk + ret) << blkbits;
+                       new_size = ((loff_t) map.m_lblk + ret) << blkbits;
 
                ext4_falloc_update_inode(inode, mode, new_size,
                                         (map.m_flags & EXT4_MAP_NEW));