BugLink: http://bugs.launchpad.net/bugs/1673541

commit c0d0e351 upstream.

Recently fallocate patch was merged and it uses
MSDOS_I(inode)->mmu_private at fat_evict_inode().  However,
fat_inode/fsinfo_inode that was introduced in past didn't initialize
MSDOS_I(inode) properly.

With those combinations, it became the cause of accessing random entry
in FAT area.

Link: http://lkml.kernel.org/r/87pohrj4i8.fsf@mail.parknet.co.jpSigned-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reported-by: Moreno Bartalucci <moreno.bartalucci@tecnorama.it>
Tested-by: Moreno Bartalucci <moreno.bartalucci@tecnorama.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>