Messages in this thread | | | Date | Tue, 10 Sep 2019 14:44:41 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] fork: fail on non-zero higher 32 bits of args.exit_signal |
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On 09/10, Eugene Syromiatnikov wrote: > > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -2562,6 +2562,9 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, > if (copy_from_user(&args, uargs, size)) > return -EFAULT; > > + if (unlikely(((unsigned int)args.exit_signal) != args.exit_signal)) > + return -EINVAL;
Hmm. Unless I am totally confused you found a serious bug...
Without CLONE_THREAD/CLONE_PARENT copy_process() blindly does
p->exit_signal = args->exit_signal;
the valid_signal(sig) check in do_notify_parent() mostly saves us, but we must not allow child->exit_signal < 0, if nothing else this breaks thread_group_leader().
And afaics this patch doesn't fix this? I think we need the valid_signal() check...
Oleg.
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