Seek back can cause crash

[karliss]

Environment information

• Operating System: Linux
• Cutter version:
• Obtained from:
  • Built from source
  • Downloaded release from Cutter website or GitHub
  • Distribution repository
• File format:

Describe the bug

To Reproduce

Not sure about exact steps but it happened, when I was testing one of undo seek shortcuts. From the debugger out seems like it might be sufficient to got to the start of history and then trying to go back again. The bug isn't 100% reliable. Maybe there are some other factors involved.

Expected behavior

No crash, no out of bounds array access.

Screenshots

Additional context

[therijalsam]

I was able to reproduce the issue on my side: it happens when you repeatedly try to undo past the very start of the seek history. What seems to be going on is that the variable tracking the current position in the seek history (topOffsetHistoryPos) gets set to -1 when you go past the beginning, but the code still tries to use that value as an index for the history array. This leads to an out-of-bounds access, which triggers the crash.

To fix this, we should make sure that before using topOffsetHistoryPos as an index, we first check that it’s in the valid range. Basically, we’d want to confirm it’s not less than zero and not past the end of the array before using it. Here’s a snippet showing how the check could look:

if (topOffsetHistoryPos >= 0 && topOffsetHistoryPos < topOffsetHistory.size()) {
    refreshDisasm(topOffsetHistory[topOffsetHistoryPos]);
}

With this in place, if a user tries to undo at the very beginning of the seek history, nothing should happen, and the app will remain stable. It might also be a good idea to disable or gray out the undo UI button when users can’t go back any further, just to make it clear.

[rquarry]

I would like to work on this, but I wasn't able to reproduce the issue.

Environment information

• Operating System: Linux
• Cutter version: cutter 2.4.0-dev-4e53fd6
• Obtained from: Built from source
• File format: .BIN, .EXE

Steps taken to reproduce:

1. Run Cutter and select file (tried .bin and .exe)
2. Navigate to various sections in disassembly (also tried graph view)
3. Seek back using Edit menu option or ALT + LEFT keys.

I did get one instance of a crash, but it was during a forward seek. Are there any additional steps to insert above to make this repeatable?