fs/partitions/ldm.c: fix oops caused by corrupted partition table

fs/partitions/ldm.c: fix oops caused by corrupted partition table

The kernel automatically evaluates partition tables of storage devices.
The code for evaluating LDM partitions (in fs/partitions/ldm.c) contains
a bug that causes a kernel oops on certain corrupted LDM partitions.
A kernel subsystem seems to crash, because, after the oops, the kernel no
longer recognizes newly connected storage devices.

The patch validates the value of vblk_size.

[[email protected]: coding-style fixes]
Signed-off-by: Timo Warns <[email protected]>
Cc: Eugene Teo <[email protected]>
Cc: Harvey Harrison <[email protected]>
Cc: Richard Russon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>