On Mon, Jul 30, 2018 at 01:26:51AM +0200, Oliver Pinter wrote: > On 7/30/18, Konstantin Belousov <kostik...@gmail.com> wrote: > >> testq %r9,%r9 > >> jz 1f > >> subq %rdx,%r8 > >> movq %r8,(%r9) << Here you access user-space, with cleared > >> RFLAGS.AC from the fault handler. > > How does this instruction access userspace ? I do not see. > > As far as I remember from 4 years, the r9 may contained a user-space > address in 10-STABLE > in the case of starting the init. I've a stac/clac pair in my internal > version, but I haven't found > yet the relevant commit message. This does not make any sense at all.
What could be a use for copyinstr(9) to pass a userspace pointer to return the copied string' length ? More, kernel must not directly access userspace, it needs to prepare for these accesses to fault. _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
