On Mon, Jul 31, 2017 at 2:52 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > Using copy_to_user instead of __copy_to_user shuts up the warning here > and is harmless, but is otherwise a completely bogus change as > the function is still using a mix of __copy_to_user and copy_to_user. > > I have not found out why create_elf_tables() uses the __copy_to_user > version in the first place, and the right answer might be that it > should simply use copy_to_user() and put_user() everywhere. IIUC, __copy*() is allowed here because the kernel is operating on an already sanity checked pointer (i.e. a freshly kernel-allocated stack). I wouldn't expect swapping in copy*() to have noticeable performance here, though if there was, it would be a constant change (the ELF tables are a per-arch fixed size). -Kees -- Kees Cook Pixel Security
