MFC r337456:
msdosfs: fixes for Undefined Behavior.
These were found by the Undefined Behaviour GsoC project at NetBSD:
Do not change signedness bit with left shift.
While there avoid signed integer overflow.
Address both issues with using unsigned type.
msdosfs_fat.c:512:42, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:521:44, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:744:14, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:744:24, signed integer overflow: -
2147483648 - 1 cannot be
represented in type 'int [20]'
msdosfs_fat.c:840:13, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:840:36, signed integer overflow: -
2147483648 - 1 cannot be
represented in type 'int [20]'
Detected with micro-UBSan in the user mode.
Hinted from: NetBSD (CVS 1.33)
git-svn-id: svn://svn.freebsd.org/base/stable/10@338180
ccf9f872-aa2e-dd11-9fc8-
001c23d0bc1f