Description of problem: We have found that when WebKitGTK+ is built with gcc-8.1.1-1.fc28 and address sanitizer enabled, it reports a stack-use-after-scope vulnerability that we believe may be a false positive. The message says: HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext (longjmp and C++ exceptions *are* supported) But none of these cases apply. The WebKit bug is https://bugs.webkit.org/show_bug.cgi?id=186980. We believe *the shadow memory might not be properly initialized*. There is a description of some assembler-level debugging in comment 24 on the WebKit bug, https://bugs.webkit.org/show_bug.cgi?id=186980#c24, which explains the suspected issue here. The other comments in the bug are probably not interesting. This issue does not occur with GCC 7, so we believe it is a regression in GCC 8. Version-Release number of selected component (if applicable): 8.1.1-1.fc28 How reproducible: Always Steps to Reproduce: Unfortunately we do not have a reduction, so to reproduce you would need to actually build WebKit, following the instructions at https://trac.webkit.org/wiki/BuildingGtk to build from git. After downloading the code, you will need to manually revert https://trac.webkit.org/changeset/233405/webkit, which I committed to work around this issue. Then, before running the 'build-webkit' script, run 'set-webkit-configuration --debug --asan'. After building, run 'run-minibrowser --gtk' and try to load http://www.example.com. I understand it's probably way too much work to reproduce, but it's also too much work for us to try to get a reduction, sorry. :( I figured some bug report might be better than none. Actual results: asan complains about stack-use-after-scope Expected results: no such complaint Additional info: In case it might be helpful, here is the complete preprocessed source of the affected file (which is huge, sorry, as it's a concatenation of eight actual source files): https://bug-186980-attachments.webkit.org/attachment.cgi?id=344030 And the corresponding generated assembly: https://bug-186980-attachments.webkit.org/attachment.cgi?id=344031
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Fedora 28 changed to end-of-life (EOL) status on 2019-05-28. Fedora 28 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. If you are unable to reopen this bug, please file a new report against the current release. If you experience problems, please add a comment to this bug. Thank you for reporting this bug and we are sorry it could not be fixed.