On Tue, Jun 05, 2018 at 04:07:15PM +0400, Ilya Matveychikov wrote: > > If you depend upon preventing kmalloc'ed temporary allocations filled > > with user-supplied data, you are screwed, plain and simple. It really can't > > be prevented, in a lot of ways that are much less exotic than mount(2). > > Most of syscall arguments are copied in, before we get any permission > > checks. It does happen and it will happen - examining them while they are > > still in userland is a nightmare in a lot of respects, starting with > > security. > > I agree that it’s impossible to completely avoid this kind of allocations > and examining data in user-land will be the bigger problem than copying > arguments to the kernel. But aside of that what’s wrong with the idea of > having the permission check before doing any kind of work? Presenting that as mitigating a vulnerability. It's neither better nor worse in that respect than the original.
