[Lldb-commits] [PATCH] D71372: [lldb] Add additional validation on return address in 'thread step-out'

Thu Dec 12 02:16:17 PST 2019

labath added a comment.

I'm not sure how easy it is to do that here, but it would certainly be nice to include these error messages in the actual error output from the "finish" command so that they are visible even without logging enabled.

As for the test, you should be able to do something similar to the tests in the `test/Shell/Unwind` folder (e.g. eh-frame-dwarf-unwind.test). I.e., you could write an assembly function which uses a non-standard frame layout, but do *not* describe that layout via .eh_frame. Then, stop in that function and try to step out...

In D71372#1780508 <https://reviews.llvm.org/D71372#1780508>, @mossberg wrote:

> Something I noticed while updating the patch was that the `GetLoadedAddressPermissions` call would succeed, even if passed an address that is obviously not mapped. In my test case I placed an int 0x22 where the return address would be, expecting the validation to fail at the `GetLoadAddressPermissions` call because 0x22 is not mapped. However, it only ended up failing when the permissions (which were empty) were checked for an execute bit. It seems to me like this might be another bug, but I'm not sure.

Are you sure there is nothing mapped at that address? I'm not a darwin expert, but I have a vague knowledge that the darwin loader (or some other component of the system) actually maps a couple of pages of unreadable memory around the address zero...

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https://reviews.llvm.org/D71372