On Wed, Sep 11, 2019 at 03:32:13PM +0100, Eugene Syromiatnikov wrote: > On Wed, Sep 11, 2019 at 04:16:36PM +0200, Christian Brauner wrote: > > On Wed, Sep 11, 2019 at 03:52:36PM +0200, Christian Brauner wrote: > > > On Wed, Sep 11, 2019 at 06:48:52AM -0700, Andrew Morton wrote: > > > > What are the user-visible runtime effects of this bug? > > The userspace can set -1 as an exit_signal, and that will break process > signalling and reaping. > > > > > Relatedly, should this fix be backported into -stable kernels? If so, > > > > why? > > > > > > No, as I said in my other mail clone3() is not in any released kernel > > > yet. clone3() is going to be released in v5.3. > > > > Sigh, I spoke to soon... Hm, this is placed in _do_fork(). There's a > > chance that this might be visible in legacy clone if anyone passes in an > > invalid signal greater than NSIG right now somehow, they'd now get > > EINVAL if I'm seeing this right. > > > > So an alternative might be to only fix this in clone3() only right now > > and get this patch into 5.3 to not release clone3() with this bug from > > legacy clone duplicated. > > And we defer the actual legacy clone fix until after next merge window > > having it stew in linux-next for a couple of rcs. Distros often pull in > > rcs so if anyone notices a regression for legacy clone we'll know about > > it... valid_signal() checks at process exit time when the parent is > > supposed to be notifed will catch faulty signals anyway so it's not that > > big of a deal. > > As the patch is written, only copy_clone_args_from_user is touched (which > is used only by clone3 and not legacy clone), and the check added
Great! > replicates legacy clone behaviour: userspace can set 0..CSIGNAL > as an exit_signal. Having ability to set exit_signal in NSIG..CSIGNAL Hm. The way I see it for clone3() it would make sense to only have < NSIG right away. valid_signal() won't let through anything else anyway... Since clone3() isn't out yet it doesn't make sense to replicate the (buggy) behavior of legacy clone, right? Christian
