On Sat, Apr 18, 2020 at 10:05:19AM +0200, Christophe Leroy wrote: > > > Le 17/04/2020 à 23:09, Eric W. Biederman a écrit : >> >> To remove the use of set_fs in the coredump code there needs to be a >> way to convert a kernel siginfo to a userspace compat siginfo. >> >> Call that function copy_siginfo_to_compat and factor it out of >> copy_siginfo_to_user32. > > I find it a pitty to do that. > > The existing function could have been easily converted to using > user_access_begin() + user_access_end() and use unsafe_put_user() to copy > to userspace to avoid copying through a temporary structure on the stack. > > With your change, it becomes impossible to do that. As Eric said we need a struct to clear all padding. Note that I though about converting to unsafe_copy_to_user in my variant as we can pretty easily do that if pre-filling the structure earlier. But I didn't want to throw in such unrelated changes for now - I'll volunteer to do it later, though.
