On Mon, Nov 7, 2022 at 3:59 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > Thanks for the patch! I need to triple-check this logic, as there have > been some overlapping (or out-of-order) LOAD bugs in the past too, and I > want to make sure we don't accidentally zero things that already got > loaded, etc. Hi Kees, Thanks for looking at my patch. I've submitted an (unprompted) v2 with an additional fix for a loading bug that could load segments after a .bss on top of .bss itself, which would overwrite any bss zeroing efforts. Note that this bug was already present in load_elf_binary. See a repro at https://github.com/heatd/elf-bug-questionmark, and the comments on the patch/repro for more info. Most ELF loading operating systems out there seem to fail on this one. As for overlapping/out-of-order LOAD segments, what kind of handling do we want here? The ELF spec (http://www.sco.com/developers/gabi/latest/ch5.pheader.html) says that "Loadable segment entries in the program header table appear in ascending order, sorted on the p_vaddr member.", so do we really want to support that? My -v2 was substantially simplified based on assuming ELF-compliant executables. > David, has there been any work on adding a way to instantiate > userspace VMAs in a KUnit test? I tried to write this myself, but I > couldn't figure out how to make the userspace memory mappings appear. > Here's my fumbling attempt: > https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=devel/kunit/usercopy > > I really wish KUnit had userspace mapping support -- I have a bunch of > unit tests that need to get built up around checking for regressions > here, etc. +1 on getting this unit-tested, this is a bit of a minefield Thanks, Pedro
