static uint32_t parse_hex(const char *s, size_t nchars, uint32_t *res)
{
	uint32_t v = 0;
	size_t n;
	int c;

	for (n = 0; n < nchars; n++) {
		c = hex(s[n]);
		if (c == (char)-1) {
			*res = TEE_ERROR_BAD_FORMAT;
			goto out;
		}
		v = (v << 4) + c;
	}
	*res = TEE_SUCCESS;
out:
	return v;
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.