On Mon, Jul 20, 2020 at 09:37:48AM -0700, Eric Biggers wrote: > How does this not introduce a massive security hole when > CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE? > > AFAICS, userspace can pass in a pointer >= TASK_SIZE, > and this code makes it be treated as a kernel pointer. Yeah, we'll need to validate that before initializing the pointer. But thinking this a little further: doesn't this mean any set_fs(KERNEL_DS) that has other user pointers than the one it is intended for has the same issue? Pretty much all of these are gone in mainline now, but in older stable kernels there might be some interesting cases, especially in the compat ioctl handlers.
