read branch targets as signed integers#18
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mike-hunhoff merged 1 commit intomandiant:mainfrom Jun 30, 2022
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mike-hunhoff
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Thank you for catching this! Yes as mentioned in our README dncil is based on the CIL parsing code found in dnlib. I have opened a new issue to double-check the types emitted by dncil's reader. |
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As defined by the standard for CIL code, targets of branch and switch instructions are stored as signed offsets [ECMA 335, Chapter III, 3.15 and 3.66].
Dncil previously read unsigned values in those cases, which caused issues for me. This is now fixed.
The code is probably based on dnlib, which in fact reads unsigned values and works just fine. Because dnlib is written in C#, an overflow will occur when negative offsets are encountered, so it still behaves like signed values were read. Such overflows do not occur in python, so the implementation has to differ from dnlib here.
There might be more of such issues hidden somewhere. Maybe it would be worth comparing the rest of the reader code to the specification as well...