Messages in this thread | | | Date | Fri, 2 Sep 2016 08:17:13 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH] fs/proc/kcore.c: Omit kernel text area for hardened usercopy feature |
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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.
-Andi
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