RE: [PATCH 2/2] mm: Add a bounds check in devm_memremap_pages()

["Alastair D'Silva" <alastair@d-silva.org>]

> -----Original Message-----
> From: David Hildenbrand <david@redhat.com>
> Sent: Tuesday, 10 September 2019 5:39 PM
> To: Alastair D'Silva <alastair@au1.ibm.com>; alastair@d-silva.org
> Cc: Andrew Morton <akpm@linux-foundation.org>; Oscar Salvador
> <osalvador@suse.com>; Michal Hocko <mhocko@suse.com>; Pavel Tatashin
> <pasha.tatashin@soleen.com>; Dan Williams <dan.j.williams@intel.com>;
> Wei Yang <richard.weiyang@gmail.com>; Qian Cai <cai@lca.pw>; Jason
> Gunthorpe <jgg@ziepe.ca>; Logan Gunthorpe <logang@deltatee.com>; Ira
> Weiny <ira.weiny@intel.com>; linux-mm@kvack.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH 2/2] mm: Add a bounds check in
> devm_memremap_pages()
> 
> On 10.09.19 04:52, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> >
> > The call to check_hotplug_memory_addressable() validates that the
> > memory is fully addressable.
> >
> > Without this call, it is possible that we may remap pages that is not
> > physically addressable, resulting in bogus section numbers being
> > returned from __section_nr().
> >
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >  mm/memremap.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/mm/memremap.c b/mm/memremap.c index
> > 86432650f829..fd00993caa3e 100644
> > --- a/mm/memremap.c
> > +++ b/mm/memremap.c
> > @@ -269,6 +269,13 @@ void *devm_memremap_pages(struct device
> *dev,
> > struct dev_pagemap *pgmap)
> >
> >  	mem_hotplug_begin();
> >
> > +	error = check_hotplug_memory_addressable(res->start,
> > +						 resource_size(res));
> > +	if (error) {
> > +		mem_hotplug_done();
> > +		goto err_checkrange;
> > +	}
> > +
> 
> No need to check under the memory hotplug lock.
> 

Thanks, I'll adjust it.

> >  	/*
> >  	 * For device private memory we call add_pages() as we only need to
> >  	 * allocate and initialize struct page for the device memory. More-
> > @@ -324,6 +331,7 @@ void *devm_memremap_pages(struct device *dev,
> > struct dev_pagemap *pgmap)
> >
> >   err_add_memory:
> >  	kasan_remove_zero_shadow(__va(res->start), resource_size(res));
> > + err_checkrange:
> >   err_kasan:
> >  	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
> >   err_pfn_remap:
> >
> 
> 
> --
> 
> Thanks,
> 
> David / dhildenb
> 

-- 
Alastair D'Silva           mob: 0423 762 819
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