Code: int utf8s_to_utf16s(const u8 *s, int len, wchar_t *pwcs)
 {
 	u16 *op;
 	int size;
 	unicode_t u;
 
 	op = pwcs;
	while (*s && len > 0) {
 		if (*s & 0x80) {
 			size = utf8_to_utf32(s, len, &u);
 			if (size < 0)
 				return -EINVAL;
 
 			if (u >= PLANE_SIZE) {
 				u -= PLANE_SIZE;
				*op++ = (wchar_t) (SURROGATE_PAIR |
						((u >> 10) & SURROGATE_BITS));
				*op++ = (wchar_t) (SURROGATE_PAIR |
 						SURROGATE_LOW |
						(u & SURROGATE_BITS));
 			} else {
				*op++ = (wchar_t) u;
 			}
			s += size;
			len -= size;
 		} else {
			*op++ = *s++;
 			len--;
 		}
 	}
 	return op - pwcs;
}

Commit Message: NLS: improve UTF8 -> UTF16 string conversion routine

The utf8s_to_utf16s conversion routine needs to be improved.  Unlike
its utf16s_to_utf8s sibling, it doesn't accept arguments specifying
the maximum length of the output buffer or the endianness of its
16-bit output.

This patch (as1501) adds the two missing arguments, and adjusts the
only two places in the kernel where the function is called.  A
follow-on patch will add a third caller that does utilize the new
capabilities.

The two conversion routines are still annoyingly inconsistent in the
way they handle invalid byte combinations.  But that's a subject for a
different patch.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
CWE ID: CWE-119
int utf8s_to_utf16s(const u8 *s, int len, wchar_t *pwcs)
static inline void put_utf16(wchar_t *s, unsigned c, enum utf16_endian endian)
{
	switch (endian) {
	default:
		*s = (wchar_t) c;
		break;
	case UTF16_LITTLE_ENDIAN:
		*s = __cpu_to_le16(c);
		break;
	case UTF16_BIG_ENDIAN:
		*s = __cpu_to_be16(c);
		break;
	}
}

int utf8s_to_utf16s(const u8 *s, int len, enum utf16_endian endian,
		wchar_t *pwcs, int maxlen)
 {
 	u16 *op;
 	int size;
 	unicode_t u;
 
 	op = pwcs;
	while (len > 0 && maxlen > 0 && *s) {
 		if (*s & 0x80) {
 			size = utf8_to_utf32(s, len, &u);
 			if (size < 0)
 				return -EINVAL;
			s += size;
			len -= size;
 
 			if (u >= PLANE_SIZE) {
				if (maxlen < 2)
					break;
 				u -= PLANE_SIZE;
				put_utf16(op++, SURROGATE_PAIR |
						((u >> 10) & SURROGATE_BITS),
						endian);
				put_utf16(op++, SURROGATE_PAIR |
 						SURROGATE_LOW |
						(u & SURROGATE_BITS),
						endian);
				maxlen -= 2;
 			} else {
				put_utf16(op++, u, endian);
				maxlen--;
 			}
 		} else {
			put_utf16(op++, *s++, endian);
 			len--;
			maxlen--;
 		}
 	}
 	return op - pwcs;
}
