Hi Wen,
As Tim points out, statically, determining that these two instructions
point to the location is a challenge in general. As Tim said, you might
be able to use the DataflowAPI to slice backwards on each register to
see if you can determine its value. However, that can't work in the most
general case.
Dynamically, you can insert instrumentation into these instructions to
calculate the effective address. Dyninst makes this easy with the
BPatch_effectiveAddressExpr method (Section 3.3 in the Dyninst
Programmer's Guide). That would allow you to gather the information at
runtime and compare them.
--bart
On 12/13/2022 11:43 AM, Tim Haines wrote:
The general problem with pointer aliasing is that there are many
different sources of memory and each presents its own challenge-
particularly heap memory. This isn't my area of expertise, but I
believe using dataflow analysis would be a place to start. DataflowAPI
won't have a single method to solve pointer aliasing because it's too
complex of a problem, but the information it provides should get you
started. Feel free to ask more questions here or open a question issue
on our Github.
Thanks.
- Tim
On 12/12/22 3:37 PM, Wen Zhang wrote:
Dear developers,
I am using Dyninst to do the static binary analysis on x86/64. And I
meet one problem with how to use Dyninst to identify two memory
locations represented by different registers that may point to the
same memory location. For example, there are two assembly codes:
mov %rax, 0x8(%rbp)
mov %rcx, 0x4(%rcx)
Even though these two memory writings look totally different,
0x8(%rbp) and 0x4(%rcx) may point to the same memory location.
I have looked at all manuals in Dyininst, but it seems nothing
related to this problem. Is there any API or method given by Dyninst
that can solve this problem?
I appreciate your feedback.
Sincerely,
Wen Zhang
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