On Fri, Sep 02, 2016 at 08:17:13AM -0700, Andi Kleen wrote: > On Fri, Sep 02, 2016 at 02:25:45PM +0200, Jiri Olsa wrote: > > One of the bullets for hardened usercopy feature is: > > - object must not overlap with kernel text > > > > which is what we expose via /proc/kcore. We can hit > > this check and crash the system very easily just by > > reading the text area in kcore file: > > > > usercopy: kernel memory exposure attempt detected from ffffffff8179a01f > > (<kernel text>) (4065 bytes) > > kernel BUG at mm/usercopy.c:75! > > > > Omitting kernel text area from kcore when there's > > hardened usercopy feature is enabled. > > That will completely break PT decoding, which relies on looking > at the kernel text in /proc/kcore. > > Need a different fix here, perhaps some special copy function > that is not hardened.
ok, I'll try to come up with something thanks, jirka
