Simplify INTERP logic for better consistency #84
Conversation
When .interp was in the first page, keep it there like the comment about FreeBSD requires. Just shift it for the new PHDR. But if .interp is already past the first page, as seen in libc.so for instance, then move its offset a whole page like we do for every other section. Then program headers follow the same logic. The conditional around startMovingSections and object type is totally removed, as it did the wrong thing for PIE binaries which otherwise look like shared libraries. We now just move all sections except low interp. Fixes dyninst#71.
|
While we do test Also, regarding CI failures, if Travis and LLVM can't get along then we should just disable the clang build. This is travis-ci/travis-ci#6120, which also has a workaround if you like. |
|
Clang on travis is disabled by #85 |
|
Thanks, Josh. I've got WIP from earlier this year on generating our PIC tests as PIE; the catch is that I need to convince the prolog spec to properly exclude all tests with assembler sources from the PIC/PIE variation. That shouldn't be hard in theory, but prolog. Final question/comment: is there any good way to generate executables with arbitrarily weird-but-legal ELF headers for testing? (Actually, if we were to do something with directed fuzzing of ELF headers and compared the loader's gripes on pre- and post-rewritten binaries, that might be better/simpler, but there's something to be said for just checking that legal->legal is an invariant.) |
|
I know that elfutils uses afl-fuzz a lot, but the directed fuzzing there is trying to crash the program under inspection. It's not oriented around producing bad output AFAIK. It still might be worthwhile to see how Dyninst fares under such input though -- AFL is good at finding really weird corner cases. For verifying rewritten output, |
When .interp was in the first page, keep it there like the comment about
FreeBSD requires. Just shift it for the new PHDR. But if .interp is
already past the first page, as seen in libc.so for instance, then move
its offset a whole page like we do for every other section. Then
program headers follow the same logic.
The conditional around startMovingSections and object type is totally
removed, as it did the wrong thing for PIE binaries which otherwise look
like shared libraries. We now just move all sections except low interp.
Fixes #71.