Re: [PATCH v4 9/9] memory: assert MemoryRegionOps callbacks are defined

[P J P <ppandit@redhat.com>]

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+-- On Wed, 16 Sep 2020, Philippe Mathieu-Daudé wrote --+
| On 8/11/20 1:41 PM, P J P wrote:
| > When registering a MemoryRegionOps object, assert that its
| > read/write callback methods are defined. This avoids potential
| > guest crash via a NULL pointer dereference.
| > 
| > Suggested-by: Peter Maydell <peter.maydell@linaro.org>
| > Reviewed-by: Li Qiang <liq3ea@gmail.com>
| > Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
| > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
| 
| Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
| 
| > ---
| >  softmmu/memory.c | 10 +++++++++-
| >  1 file changed, 9 insertions(+), 1 deletion(-)
| > 
| > Update v4: add Reviewed-by tag
| >   -> https://lists.nongnu.org/archive/html/qemu-devel/2020-07/msg05324.html
| > 
| > diff --git a/softmmu/memory.c b/softmmu/memory.c
| > index af25987518..1f4b37b3a6 100644
| > --- a/softmmu/memory.c
| > +++ b/softmmu/memory.c
| > @@ -1485,7 +1485,13 @@ void memory_region_init_io(MemoryRegion *mr,
| >                             uint64_t size)
| >  {
| >      memory_region_init(mr, owner, name, size);
| > -    mr->ops = ops ? ops : &unassigned_mem_ops;
| > +    if (ops) {
| > +        assert(ops->read || ops->read_with_attrs);
| > +        assert(ops->write || ops->write_with_attrs);
| > +        mr->ops = ops;
| > +    } else {
| > +        mr->ops = &unassigned_mem_ops;
| > +    }
| >      mr->opaque = opaque;
| >      mr->terminates = true;
| >  }
| > @@ -1663,6 +1669,8 @@ void memory_region_init_rom_device_nomigrate(MemoryRegion *mr,
| >  {
| >      Error *err = NULL;
| >      assert(ops);
| > +    assert(ops->read || ops->read_with_attrs);
| > +    assert(ops->write || ops->write_with_attrs);
| >      memory_region_init(mr, owner, name, size);
| >      mr->ops = ops;
| >      mr->opaque = opaque;
| > 

@Paolo...ping!

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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