On 09/14/2011 10:02 AM, David Gibson wrote:
It is quite common to have a MemoryRegion with size of INT64_MAX. When processing alias regions in render_memory_region() it's quite easy to find a case where it will construct a temporary AddrRange with a non-zero start, and size still of INT64_MAX. When means attempting to compute the end of such a range as start + size will result in signed integer overflow.This integer overflow means that addrrange_intersects() can incorrectly report regions as not intersecting when they do. For example consider the case of address ranges {0x10000000000, 0x7fffffffffffffff} and {0x10010000000, 0x10000000} where the second is in fact included completely in the first.
Good catch, thanks for digging this out.
This patch rearranges addrrange_intersects() to avoid the integer overflow, correcting this behaviour.
I expect that the bad behaviour can still be triggered, for example by pointing aliases towards the end of very large regions. Not that I expect this to occur in practice.
I think we should move towards using __int128 internally. Is there any relevant host which does not support __int128?
Meanwhile, applied to memory/core, and will request a pull shortly. -- error compiling committee.c: too many arguments to function
