Vector35 / Vector35/binaryninja-api
Fixup chains not properly handled in Mach-O view
Nobody has claimed this yet.
- Dominant language
- C++
- Stars
- 1.3k
- Forks
- 298
- Avg merge
- 5d 5h
- Merged PRs (30d)
- 19
Description
Version and Platform:
- Version: Binary Ninja 5.3.8844-dev
- Edition: Commercial
- OS: macOS
- OS Version: Tahoe 26.1 (
25B78) - CPU Architecture: M2 Pro
Bug Description:
For some iOS binaries, dyld_chained_ptr_64_bind pointers (format DYLD_CHAINED_PTR_64) are not properly handled in fixup chains. These are heavily used in the __got section:
Steps To Reproduce:
- Download this example IPA (should work with other ones).
- Load the
Deltabinary it contains with Binary Ninja
Expected Behavior:
Every bind pointer should be bound to its corresponding symbol, by navigating structures of the LC_DYLD_CHAINED_FIXUPS load command.
I suspect symbols are resolved correctly at some point as the following log message appear for every unbound pointer:
[BinaryView.MachoView] Failed to find external symbol "<symbol-name>", couldn't bind symbol at <address>
Contributor guide
No contributing guide indexed for this repository
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by loading the Delta binary from the linked IPA and examining Mach-O handling for the LC_DYLD_CHAINED_FIXUPS load command, especially DYLD_CHAINED_PTR_64 bind pointers in __got. Use the repeated “Failed to find external symbol” log messages to trace the unbound pointers. Done means every bind pointer resolves to its corresponding symbol.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- reverse-engineering
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100