BUG: memcmp(): Accessing invalid memory location

[Benjamin Herrenschmidt]

On Thu, 2019-01-24 at 19:48 +0530, Chandan Rajendra wrote:
> - Here we execute "LD rB,0,r4". In the case of this bug, r4 has an unaligned
>   value and hence ends up accessing the "next" double word. The "next" double
>   word happens to occur after the last page mapped into the kernel's address
>   space and hence this leads to the previously listed oops.
>   

This is interesting ... should we mark the last page of any piece of
mapped linear mapping as reserved to avoid that sort of issue ?

Nick ? Aneesh ?

Cheers,
Ben.