DevPathToTextUsbWWID allocates a separate copy of the SerialNumber
string to append a null terminator if the original string is not null
terminated. However, by using AllocateCopyPool, it tries to copy
'Length + 1' words from the existing string containing 'Length'
characters into the target string. Split the copy out to only copy
'Length' characters instead.
This was reported by GCC's -Wstringop-overread when compiling a copy
of this routine included in a library on FreeBSD.
Signed-off-by: John Baldwin <jhb@FreeBSD.org>
a859f4fc03