Messages in this thread | | | Subject | Re: [PATCH] powerpc: Perform a bounds check in arch_add_memory | From | "Alastair D'Silva" <> | Date | Tue, 27 Aug 2019 16:39:56 +1000 |
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On Tue, 2019-08-27 at 08:28 +0200, Michal Hocko wrote: > On Tue 27-08-19 15:20:46, Alastair D'Silva wrote: > > From: Alastair D'Silva <alastair@d-silva.org> > > > > It is possible for firmware to allocate memory ranges outside > > the range of physical memory that we support (MAX_PHYSMEM_BITS). > > Doesn't that count as a FW bug? Do you have any evidence of that in > the > field? Just wondering... >
Not outside our lab, but OpenCAPI attached LPC memory is assigned addresses based on the slot/NPU it is connected to. These addresses prior to: 4ffe713b7587 ("powerpc/mm: Increase the max addressable memory to 2PB") were inaccessible and resulted in bogus sections - see our discussion on 'mm: Trigger bug on if a section is not found in __section_nr'. Doing this check here was your suggestion :)
It's entirely possible that a similar problem will occur in the future, and it's cheap to guard against, which is why I've added this.
-- Alastair D'Silva Open Source Developer Linux Technology Centre, IBM Australia mob: 0423 762 819
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