On Sat, Oct 21, 2023 at 04:36:19PM -0700, Kees Cook wrote: > On October 20, 2023 1:36:36 PM PDT, andy.shevchenko@xxxxxxxxx wrote: > >That said, if you or anyone has ideas how to debug futher, I'm all ears! > > I don't think this has been tried yet: > > When I've had these kind of hard-to-find glitches I've used manual > built-binary bisection. Assuming you have a source tree that works when built > with Clang and not with GCC: > - build the tree with Clang with, say, O=build-clang > - build the tree with GCC, O=build-gcc > - make a new tree for testing: cp -a build-clang build-test > - pick a suspect .o file (or files) to copy from build-gcc into build-test > - perform a relink: "make O=build-test" should DTRT since the copied-in .o > files should be newer than the .a and other targets > - test for failure, repeat > > Once you've isolated it to (hopefully) a single .o file, then comes the > byte-by-byte analysis or something similar... > > I hope that helps! These kinds of bugs are super frustrating. I'm sorry, but I can't see how this is not an error prone approach. If it's a timing issue then the arbitrary object change may help and it doesn't prove anything. As earlier I tried to comment out the error message, and it worked with GCC as well. The difference is so little (according to Linus) that it may not be suspectible. Maybe I am missing the point... -- With Best Regards, Andy Shevchenko
