On Wed, Oct 20, 2021 at 12:44:00PM -0500, Eric W. Biederman wrote: > Use force_fatal_sig instead of calling do_exit directly. This ensures > the ordinary signal handling path gets invoked, core dumps as > appropriate get created, and for multi-threaded processes all of the > threads are terminated not just a single thread. > > When asked Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx> said [1]: > > ebiederm@xxxxxxxxxxxx (Eric W. Biederman) asked: > > > > > Why does do_syscal_user_dispatch call do_exit(SIGSEGV) and > > > do_exit(SIGSYS) instead of force_sig(SIGSEGV) and force_sig(SIGSYS)? > > > > > > Looking at the code these cases are not expected to happen, so I would > > > be surprised if userspace depends on any particular behaviour on the > > > failure path so I think we can change this. > > > > Hi Eric, > > > > There is not really a good reason, and the use case that originated the > > feature doesn't rely on it. > > > > Unless I'm missing yet another problem and others correct me, I think > > it makes sense to change it as you described. > > > > > Is using do_exit in this way something you copied from seccomp? > > > > I'm not sure, its been a while, but I think it might be just that. The > > first prototype of SUD was implemented as a seccomp mode. > > If at some point it becomes interesting we could relax > "force_fatal_sig(SIGSEGV)" to instead say > "force_sig_fault(SIGSEGV, SEGV_MAPERR, sd->selector)". > > I avoid doing that in this patch to avoid making it possible > to catch currently uncatchable signals. > > Cc: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Andy Lutomirski <luto@xxxxxxxxxx> > [1] https://lkml.kernel.org/r/87mtr6gdvi.fsf@xxxxxxxxxxxxx > Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Yeah, looks good. Should be no visible behavior change. Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
