On 11/12/21 at 10:08am, David Hildenbrand wrote: > > > "that allows supervisor mode programs to optionally set user-space > > > memory mappings so that access to those mappings from supervisor mode > > > will cause a trap. This makes it harder for malicious programs to > > > "trick" the kernel into using instructions or data from a user-space > > > program" > > > > OK, probably. I thought it's triggered in access_ok(), and tried to > > figure out why. But seems we should do something to check this in > > access_ok(), otherwise the logic of clear_user/_clear_user is not so > > reasonable. Anyway, I have learned it, thanks a lot for digging it out. > > > > By the way, I can't open above wiki article, found below commit from > > hpa. Maybe we can add some into log to tell this, not strong opinin, > > leave it to you. > > Yes, now that we know the root cause I'll add some more details to the > patch description and resend -- thanks Baoquan! Thanks for sending v2.