Messages in this thread | | | Date | Wed, 10 Sep 2014 23:13:58 +0800 | From | Baoquan He <> | Subject | Re: [PATCH 1/4] kaslr: check user's config too when handle relocations |
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On 09/10/14 at 11:04am, Vivek Goyal wrote: > On Wed, Sep 10, 2014 at 10:53:34PM +0800, Baoquan He wrote: > > On 09/10/14 at 10:30am, Vivek Goyal wrote: > > > In case of kdump we will have to pass nokaslr, as we don't want kernel > > > to move as it could stomp over other things we have loaded. > > > > For kdump and kexec nokaslr is unnecessary. As you know we always > > call add_buffer with buf_end as 1, this will cause kernel loaded at the > > top of available memory. E.g on my pc with 16G memory, kexec kernel will > > be put nearby 16G, so no random location choosing happen as I said in > > above. For kdump, if reserved memory is at 500M~700M, then kernel will > > be put nearby 700M, the random location choosing also never happen. > > > > In fact, for some cases I need change kexec-tools user app code, to make > > kernel be put from down to top. > > I think we can't rely on where exactly in memory kexec-tools places the > kernel. For kdump case we will have to pass nokaslr to make sure that > kaslr does not move kernel.
In fact with this fix, it still works though kdump kernel is relocated if kdump kernel is put in a low addr of reserved memory. But I am fine with it that adding nokaslr to make it safer.
> > Thanks > Vivek
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