I came across this today. Whip down to question 11 where is reads…
I want to use SWAP or COMPCACHE to increase the available RAM on my Android phone. Is that safe ?
The answer there states compcache is safe _while swap is considered _unsafe. A closer looks tells a slightly different story, however.
Compcache is a system that conserves memory by compressing a portion of it. This portion is readable by the root user at /dev/block/ramzswapN, where N is some number. This means that any application running on a device utilizing compcache could have portions of its address space readable from the above mentioned path.
I have a rooted device running custom firmware with compcache installed. So, I tried reading data from the cache after using some apps that contained sensitive information. As I expected, I found that there were pieces of that information in the cache. As with the case I explored previously, passwords and encryption don’t help here.
So, would I call compcache any safer than swap? Nope.