tree f845494ae3eaa257256095e009b55885517de0c5
parent cc37f75a9ffbbfcb1c3297534f293c8284e3c5a6
author Phillip Lougher <phillip@squashfs.org.uk> 1325559493 +0000
committer Phillip Lougher <phillip@squashfs.org.uk> 1325563243 +0000

Squashfs: fix i_blocks calculation with extended regular files

The le64_to_cpu() forces the calculation to be unsigned, with
the effect that it can underflow leading to an incorrect large
value.

This bug only triggers in rare(ish) circumstances, an empty file
encoded as an extended regular file or a completely sparse file.
Normally empty files are encoded as a regular file rather than as
an extended regular file (and the regular file i_blocks calculation
doesn't have this bug).  To save space regular file inodes are
optimised to encode the most commonly occurring files.  Less
common regular files are encoded using extended regular file inodes
which contain extra information.

Empty files with nlinks greater than 1, and or empty files
with extended attributes are encoded using extended regular file
inodes and they will hit this bug.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>