On Sun, Jun 19, 2016 at 2:19 PM, Oleg Nesterov <o...@redhat.com> wrote: > Let me first thank Pedro who has already replied! > > And I have to admit I will need to re-read his explanations after > sleep to (try to) convince myself I fully understans the problems ;) > Too late for me. > > Right now I have nothing to add, but > > On 06/18, Andy Lutomirski wrote: >> >> @@ -922,16 +922,7 @@ static int putreg32(struct task_struct *child, unsigned >> regno, u32 value) >> R32(esp, sp); >> >> case offsetof(struct user32, regs.orig_eax): >> - /* >> - * A 32-bit debugger setting orig_eax means to restore >> - * the state of the task restarting a 32-bit syscall. >> - * Make sure we interpret the -ERESTART* codes correctly >> - * in case the task is not actually still sitting at the >> - * exit from a 32-bit syscall with TS_COMPAT still set. >> - */ >> regs->orig_ax = value; >> - if (syscall_get_nr(child, regs) >= 0) >> - task_thread_info(child)->status |= TS_COMPAT; > > I agree it would be nice to remove this code, but then it is not clear > how/when we should sign-extend regs->ax.. > > And this leads to another question, why do we actually need to set/clear > TS_COMPAT in set_personality_ia32() ??
I have no idea. Legacy junk? Maybe so audit sees execution of a 64-bit task as a 64-bit sys_execve return even if the task was 32-bit before execve? --Andy
