Different regions have the same allocation address

Question

I examine address space of process in Windows 7. I use VirtualQueryEx function, and this is some part of my example, where handleOfProcess_ is handle of some process:

MEMORY_BASIC_INFORMATION mbi;
bool ok = (VirtualQueryEx(handleOfProcess_, (LPCVOID)0x00020000, &mbi, sizeof(mbi))== sizeof(mbi));
ok = (VirtualQueryEx(handleOfProcess_, (LPCVOID)0x00021000, &mbi, sizeof(mbi))== sizeof(mbi));

When I do debug, I see, that the AllocationBase of 0x00020000 is 0x00020000, and the Allocationbase of 0x00021000 is 0x00000000, which is the allocationBase of another region.

How can it happen?

Thanks to all.

0x1000 in first call (MEM_COMMIT), and 0x10000 in second call (MEM_FREE) — user3245337, Mar 10 '14 at 23:05

score 1 · Accepted Answer · answered Mar 10 '14 at 23:11

1

From the documentation for MEMORY_BASIC_INFORMATION:

For free pages, the information in the AllocationBase, AllocationProtect, Protect, and Type members is undefined.

answered Mar 10 '14 at 23:11

Harry Johnston

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Thanks, so how can i check whether free block is in a region with some AllocationBase address? Richter don't check in VMMap program whether block is free or not. – user3245337 Mar 10 '14 at 23:44
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If a block is free, then by definition it isn't in an allocated region, so there's nothing to check. I don't understand your second sentence at all; who or what is Richter? – Harry Johnston Mar 11 '14 at 02:14
Yes you are right. I already understand what i want, so you don't need to understand my second sentence :) thanks again. – user3245337 Mar 11 '14 at 19:29

Different regions have the same allocation address

1 Answers1