The assembly files in libaom (*.asm) get built with nasm and are not built with CET support. As a result the final library libaom.so does not get built with shadow stack and IBT markup. To enable shadow stack support one must: 1. Emit the ENDBR instruction at the top of every function that is the target of an indirect branch. 2. Add a .gnu.property note that indicates support for SHSTK and IBT, either by adding assembler directives (see /usr/lib/gcc/x86_64-redhat-linux/13/include/cet.h for example) or by forcing the annotation in the linker using -Wl,-z,shstk -Wl,-z,ibt AFAICT, none of the assembler code switches stacks, but if it does, it would need a more involved fix to update the shadow stack pointer. Without this, when Fedora is booted with a shadow stack enabled kernel (patches are currently in review upstream[1]), a number of php and python packages fail to build because of lacking SHSTK support in libaor. [1] https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/ Reproducible: Always
I don't think any of the package maintainers are qualified to *correctly* do what's asked here (without introducing bugs), at least not without significant help from upstream. And since that upstream is Google ... well, I'm wouldn't be holding my breath.
Sent upstream: https://bugs.chromium.org/p/aomedia/issues/detail?id=3466
This bug appears to have been reported against 'rawhide' during the Fedora Linux 39 development cycle. Changing version to 39.
Would the packages still fail to build if Shadow Stack (SHSTK) support was added without adding Indirect Branch Tracking (IBT) support? Did you try such a build by adding `-Wl,-z,shstk` to the linker flags?
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