lib/ucs2_string: Split out ucs2_as_utf8_l() taking a separate limit

ucs2_as_utf8() takes a maxlength argument, which specifies how many
bytes the function is permitted to store into the destination buffer.

The same value is used as an upper bound for the ucs2_strnlen()
invocation, which is reasonable in the general case, as each UCS-2
character produces at least one byte of UTF-8 output, and so there is
never a need to process more than 'maxlength' UCS-2 characters.

However, if the UCS-2 string is not NUL terminated, ucs2_strnlen() may
read past the end of the buffer if 'maxlength' is set to a high value.

Current callers pass UCS-2 strings that are expected to be NUL
terminated, but for processing the load options in the EFI stub, a
version is needed that takes a separate limit argument. So split that
off from the current implementation.

Reviewed-by: Vincent Mailhol <mailhol@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

0 files changed, 0 insertions, 0 deletions