Luckily, you don't have to sound like this. Look at the highest finger being used (4 in the case of octaves, 3 in the case of fingered octaves). Look at the smallest knuckle on this finger (the one closest to your fingernail, you knucklehead). If you sound like ... well, you know, which you probably do if you're reading this blog, chances are it's bent too far in the convex direction. Flatten it out a little.
Now you can shift your arm a little bit towards the scroll and place your lower finger a little lower (first, in the case of octaves). Boom. Problem solved. Or at least ameliorated.
Do yourself a favor and watch this video clip for five seconds. Sean Lee, one of the most outstanding young violinists in the world, plays octaves with effortless grace in this example. Notice how flat the knuckles in his third and fourth finger are. Learn from the master.