Use safer string manipulation functions when dealing with a
user-provided string in kprobe_lookup_name().
Reported-by: NDavid Laight <David.Laight@ACULAB.COM>
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>