Graph should update after editing branch instruction

[elikaski]

Environment information

• Operating System: Ubuntu 18.04.3
• Cutter version: 1.10.3
• Obtained from:
  • [x] Built from source
  • [ ] Downloaded from release
  • [ ] Distribution repository
• File format: ELF

Describe the bug After editing a conditional branch instruction (jz, jle, etc...) to a non-conditional branch instruction (jmp, nop, etc...), the graph does not update its basic blocks and branch arrows. (see below screenshots). Similarly, when editing a non-conditional branch instruction (mov, nop, etc...) to a branch instruction (conditional or non-conditional), the graph does not update accordingly.

To Reproduce

Steps to reproduce the behavior:

1. Go to Graph Display
2. Right click on a conditional branch instruction (the last instruction of a basic block)
3. Edit->Nop Instruction

Similarly,

1. Go to Graph Display
2. Right click on any instruction that is not the last of its basic block
3. Edit->Instruction
4. Type in "jmp 0x1337" or "jz 0x1337"

Expected behavior It makes sense that after editing an instruction that affects the control flow, the graph will update accordingly. For example, if I modify a "jz 0x1337" to a "nop", I expect that the current basic block and the following basic block (the one where the branch is not taken) will merge into one. Similarly, if I modify a "nop" to a "jz 0x1337", I expect that the current basic block will end, and 2 new arrows will appear, pointing to 2 new basic blocks.

Note that the graph does not update even after relaunching Cutter and opening the same project.

Screenshots Before edit:

After edit:

The block that belongs to the red arrow should be combined into the basic block, and the block that belongs to the green arrow should not appear.

Similarly, Before edit:

After edit to jmp (non-conditional branch):

I expect the basic block will 'end' on the jmp instruction, and only one arrow will be coming out of it.

After edit to je (conditional branch): I expect that basic block will 'end' on the je instruction, and 2 new arrows will be created from it. One to a new basic block that will contain the following "add" command, and one to the basic block at 0x1184.

Additional context

[ITAYC0HEN]

Thank you for a detailed explanation! This is indeed a bug, and it caused by radare2. Few months ago, I opened an issue in radare2 regarding this. You can check it out in https://github.com/radareorg/radare2/issues/15644

I will keep this detailed issue you opened as a reference here as well. Meantime, a workaround I can suggest is to undefined and re-define the function.

Thank you!