I have two secret values $a$ and $b$ (i.e. they are arbitrary values). I mask them as follow:
$v_1=r_1a+r_2$
$v_2=r_1(b-a)$
where $r_1$ and $r_2$ are uniformly random values. I send $v_1$ and $v_2$ to a malicious server, and ask him to compute $v_1+v_2=r_1b+r_2$
Question: Given $v_1$ and $v_2$, can the server learn anything about $a$ and $b$?
Note: We know that if the server learns $r_1$ or $r_2$ it can figure out the values $a$ and $b$ too.
Edit: I consider modular operations, so they are done mod $p$ where $p$ is a large prime number. So $r_i$ is picked uniformly at random from the field $\mathbb{F}_p$