Messages in this thread | | | Date | Mon, 21 Dec 2020 11:12:28 -0600 | From | Segher Boessenkool <> | Subject | Re: [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs() |
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On Mon, Dec 21, 2020 at 04:42:23PM +0000, David Laight wrote: > From: Segher Boessenkool > > Sent: 21 December 2020 16:32 > > > > On Mon, Dec 21, 2020 at 04:17:21PM +0100, Christophe Leroy wrote: > > > Le 21/12/2020 à 04:27, Xiaoming Ni a écrit : > > > >Since the commit 2b0e86cc5de6 ("powerpc/fsl_booke/32: implement KASLR > > > >infrastructure"), the powerpc system is ready to support KASLR. > > > >To reduces the risk of invalidating address randomization, don't print the > > > >EIP/LR hex values in dump_stack() and show_regs(). > > > > > I think your change is not enough to hide EIP address, see below a dump > > > with you patch, you get "Faulting instruction address: 0xc03a0c14" > > > > As far as I can see the patch does nothing to the GPR printout. Often > > GPRs contain code addresses. As one example, the LR is moved via a GPR > > (often GPR0, but not always) for storing on the stack. > > > > So this needs more work. > > If the dump_stack() is from an oops you need the real EIP value > on order to stand any chance of making headway.
Or at least the function name + offset, yes.
> Otherwise you might just as well just print 'borked - tough luck'.
Yes. ASLR is a house of cards. But that isn't constructive wrt this patch :-)
Segher
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