On Wed, Apr 10, 2019 at 4:12 PM Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > You've explained *what* it does again, but not *why*. *Why* do you want > hardened usercopy to detect copies across page boundaries, when there is no > actual buffer overflow? But that *is* how it determines it was a buffer overflow: "if you cross page boundaries (of a non-compound allocation), it *is* a buffer overflow". This assertion, however, is flawed because many contiguous allocations are not marked as being grouped together when it reality they were. It was an attempt to get allocation size information out of the page allocator, similar to how slab can be queries about allocation size. I'm open to improvements here, since it's obviously broken in its current state. :) -- Kees Cook
